Ancients models have a low roll acceleration ( <0.06) and newest racing models don´t have a pretty number ( Between 0.1-0.2). Better a seasickness
and be faster or better a great stomach and be slower?

Comments guys?

Best winds

A sea sick MD !! :D Te-he... doc, I thought you would have a cure for that ;)

The low roll accelleration may be due to very heavy ancient boats. Newer technology boats are much lighter and should respond faster.

As far as I know any boat becomes more unpleasant to be aboard the faster it goes, it becomes worse if the water becomes unfriendly. The only way to travel on water is to adjust speed to where it becomes comfortable or bearable enough for the conditions.

I have never been seasick, on many boats (power) However I was on a 'houseboat' once and this thing didn't move right on the water. Didn't get seasick but felt very uncomfortable. So I guess the boat's sensitivity of movement could also play a role.

The cure is staying onshore, but it´s rather bored Fanie.

Best winds

It's the period of the acceleration that matters as much or more than the amplitude. The human body is most sensitive, in terms of motion sickness incidence at around 10-second periods (0.1 Hz) ..and virtually insensitive at periods of 1-sec or thereabouts. O'Hanlon and McCauley's MSI curves define the sensitivity over the whole range.

I've seen where a huge number of passengers got sick on a wavepiercing cat traveling at 40 knots with 'only' 0.08 gRMS acceleration (but at around 8 second period) and virtually none sick on a bouncy SES traveling the same speed but experiencing 0.16 gRMS, where the motion period is less than 1 second (>1 Hz)

I think stayong on shore is the ailment, I get sick if I stay off the water for too long... ;) Was on the water a while back... was enjoying it so much I almost forgot to fish :D Forced myself :rolleyes:

Ok, so to prevent seasickness to some extent one can then also change direction (or speed) since at a given speed, upwind and downwind should provide different frequencies.

Antonio,

There is one only know sure cure for seasickness....
Cling to a gum tree.

[QUOTE=BMcF;175881]It's the period of the acceleration that matters as much or more than the amplitude. The human body is most sensitive, in terms of motion sickness incidence at around 10-second periods (0.1 Hz) ..and virtually insensitive at periods of 1-sec or thereabouts. O'Hanlon and McCauley's MSI curves define the sensitivity over the whole range.

I´m really impressive as Md with this comment. Congratulations, I´ve never seen this "paper" ( the way we talk about science articles). From now on, i´ll be waiting much more information about the influence of the acceleration on the human body . This kind of contents might be really interesting to the people.

[QUOTE=BMcF;175881]It's the period of the acceleration that matters as much or more than the amplitude. The human body is most sensitive, in terms of motion sickness incidence at around 10-second periods (0.1 Hz) ..and virtually insensitive at periods of 1-sec or thereabouts. O'Hanlon and McCauley's MSI curves define the sensitivity over the whole range.

I´m really impressive as Md with this comment. Congratulations, I´ve never seen this "paper" ( the way we talk about science articles). From now on, i´ll be waiting much more information about the influence of the acceleration on the human body . This kind of contents might be really interesting to the people.

The results of O'Hanlon et al are embodied in ISO 2631. That should be relatively easy for you to track down vice trying to obtain some of their original publications.

I assess vessel habitability (motion sickness, fatigue-decreased-proficiency, task interruption, etc) and design ship stabilization systems..so the work of O'Hanlon, Miwa, Stark, etc on the effects of various motions and whole body vibration on humans is of particular interest to me.

........... Better a seasickness
and be faster or better a great stomach and be slower?........

Boats (as opposed to ships) incapacitate their crew more from vertical acceleration due to heaving and pitching than other motions.

Ted Brewer summed up small boat comfort reasonably well with his "Comfort Factor" . Unfortunately habitability (other than interior layout) is not a great concern of many yacht designers. I think motion comfort is the main criterion for an enjoyable passage. Many experienced long distance cruisers find that comfort at sea is considerably more important than crisp noon to noon runs. This is also my own experience.

Motion Comfort Ratio was developed by Boat Designer Ted Brewer. The formula predicts the speed of the upward and downward motion of the boat as it encounters waves and swells. The faster the motion the more uncomfortable the passengers. Thus, the formula predicts the overall comfort of a boat when it is underway. Higher values denote a more comfortable ride. As the Displacement increases the motion comfort ratio will increase. As the length and beam increases the motion comfort ratio will decrease.

MCR = Disp / (2/3*((7/10 * LWL)+(1/3 *LOA))*Beam4/3 )

So, as you can see below of my comment you have some types of sailboats and their motion comfort ratio after the application of that formula:

Alberg 35 Sloop, Motion Comfort=36.48
Alberg 37, Motion Comfort=39.3
Allied Mistress 39, Motion Comfort=35.62
Allied Seawind, Motion Comfort=39.69
Allied Seawind II, Motion Comfort=36.89
Alpa A42 (S&S), Motion Comfort=44.85
Alpa A42 (S&S) Half-loaded, Motion Comfort=51.22
Amel Maramu, Motion Comfort=36.05
Amphitrite 43, Motion Comfort=37.67
Amphitrite MS45, Motion Comfort=40.15
Antigua, Motion Comfort=44.99
Baba 35, Motion Comfort=41.94
Bayfield 40, Motion Comfort=35.26
Bolger Ataraxia, Motion Comfort=36.21
Bolger Barnowl, Motion Comfort=37.85
Bolger Leeboard Catboat, Motion Comfort=38.08
Bolger Schuyt Houseboat, Motion Comfort=35.83
Brewer Orca, Motion Comfort=45.23
Brewer Sandingo, Motion Comfort=35.5
Brewer Sunshine, Motion Comfort=46.05
Brewer Thursday's Child, Motion Comfort=44.32
Bristol 35.5, Motion Comfort=35.23
Bristol 40, Motion Comfort=36.57
Bristol 41.1, Motion Comfort=37.85
Bristol 45.5, Motion Comfort=42.97
Bristol Channel Cutter, Motion Comfort=36.89
Brolga 33, Motion Comfort=37.36
Buehler Archimedes, Motion Comfort=52.8
Buehler Dragonfly 50, Motion Comfort=48.88
Buehler Emily, Motion Comfort=37.55
Buehler Juna, Motion Comfort=45.93
Buginese Schooner, Motion Comfort=43.95
CSY 37, Motion Comfort=35.57
CSY 44, Motion Comfort=46.66
CSY 44 Pilothouse Ketch, Motion Comfort=47.94
CT 34, Motion Comfort=37.68
CT 54, Motion Comfort=51.36
CT50, Motion Comfort=50.7
Cabo Rico 37, Motion Comfort=36.61
Cabo Rico 38, Motion Comfort=38.96
Cabo Rico 42, Motion Comfort=36.77
Cabo Rico Tiburon 36, Motion Comfort=39.23
Cal 2-46, Motion Comfort=39.72
Cal 48, Motion Comfort=36.06
Caliber 47LRC, Motion Comfort=38.51
Cambria 44, Motion Comfort=35.56
Camper Nicholson 32, Motion Comfort=43.52
Cape Dory 36, Motion Comfort=35.5
Cape George 31, Motion Comfort=42.16
Cape George 34, Motion Comfort=44.69
Cape George 36, Motion Comfort=47.54
Chatam 330, Motion Comfort=41.76
Cheoy Lee Clipper 36, Motion Comfort=37.41
Cheoy Lee Clipper 42, Motion Comfort=38.59
Cheoy Lee Offshore 31, Motion Comfort=35.45
Cheoy Lee Offshore 50, Motion Comfort=43.51
Cheoy Lee Robb 35 Yawl, Motion Comfort=37.77
Cherubini 44, Motion Comfort=42.05
Cherubini 48, Motion Comfort=41
Chris Craft Sail Yacht 35, Motion Comfort=37.32
Colin Archer 37 Pilot Cutter, Motion Comfort=54.67
Columbia 38, Motion Comfort=35.01
Columbia 40, Motion Comfort=38.29
Columbia 41 Shoal Sloop, Motion Comfort=38.21
Columbia 45, Motion Comfort=40.32
Columbia 45 Sloop, Motion Comfort=35.82
Columbia 50 (Tripp), Motion Comfort=46.64
Columbia 56, Motion Comfort=49.97
Columbia 56 MS, Motion Comfort=49.97
Columbia 57, Motion Comfort=49.77
Colvin Saugeen Witch, Motion Comfort=35.29
Concordia Yawl, Motion Comfort=38.99
Corbin 39, Motion Comfort=42.7
Cornish Crabber Pilot 30, Motion Comfort=35.37
Coronado 35 Ketch (SK), Motion Comfort=36.01
Coronado 35 Sloop (SK), Motion Comfort=36.01
Coronado 41, Motion Comfort=37.95
Creala 40, Motion Comfort=39.34
Crealock 40, Motion Comfort=37.23
Crealock 40 Twin Stay, Motion Comfort=39.34
Dickerson 41, Motion Comfort=37.83
Dix Hout Bay 30, Motion Comfort=37.3
Downeast 45 Ketch, Motion Comfort=45.4
Dreadnought 32, Motion Comfort=47.49
Duncanson 29, Motion Comfort=39.9
Duncanson 40, Motion Comfort=43.71
Endeavor 37, Motion Comfort=38.19
Endeavour 40 Sloop, Motion Comfort=36.59
Endeavour 43 Ketch, Motion Comfort=39.54
Ericson 39, Motion Comfort=35.25
Ericson 41, Motion Comfort=35.57
FISHER 30, Motion Comfort=41.43
Fantasia 35 MK II, Motion Comfort=50.99
Fast Passage 39, Motion Comfort=38.72
Folkes 39 Cutter (Steel), Motion Comfort=41.86
Formosa 46, Motion Comfort=37.8
Formosa 51, Motion Comfort=53.28
Freedom 45, Motion Comfort=35.18
Fuji 32 Ketch, Motion Comfort=35.73
Fuji 35, Motion Comfort=40.74
Fuji Ketch 45, Motion Comfort=43.45
Gail Storm (Exp. Design), Motion Comfort=35.5
Gartside Cutter 30 Ft, Motion Comfort=49.91
Gibbons 42, Motion Comfort=35.57
Gilbert Scarper Flo, Motion Comfort=37.77
Giles 38, Motion Comfort=40.78
Golden Hind 31 MKll, Motion Comfort=39.33
Grampian Classic 31, Motion Comfort=36.13
Gulf 32 Pilothouse, Motion Comfort=39.57
Gulfstar 50ft Ketch, Motion Comfort=38.56
Hallberg Rassy HR39, Motion Comfort=35.7
Hans Christian 38, Motion Comfort=43.52
Hans Christian 41T, Motion Comfort=46.46
Hardin 45 Ketch, Motion Comfort=43.36
Hartley 36, Motion Comfort=48.17
Hartley Fijian 43 Cutter, Motion Comfort=45.16
Heritage 35 By McCurdy & Rhodes, Motion Comfort=37.83
Herreshoff Araminta, Motion Comfort=36.78
Herreshoff Block Island Boat, Motion Comfort=50.35
Herreshoff Bounty, Motion Comfort=46.24
Herreshoff Diddikai, Motion Comfort=47.75
Herreshoff Double-ended Sloop, Motion Comfort=40.29
Herreshoff Joann, Motion Comfort=54.69
Herreshoff Leeboard Ketch, Motion Comfort=41.04
Herreshoff Lifeboat Ketch, Motion Comfort=44.19
Herreshoff Manana, Motion Comfort=49.81
Herreshoff Mobjack, Motion Comfort=50.33
Herreshoff Nereia, Motion Comfort=40.23
Herreshoff Persephone, Motion Comfort=51.95
Herreshoff Restricted Sail Area Cruiser, Motion Comfort=38.13
Herreshoff Santee, Motion Comfort=47.97
Herreshoff Unicorn, Motion Comfort=51.8
Herreshoff Wagon Box, Motion Comfort=42.98
Herreshoff Walrus, Motion Comfort=54.75
Hillyard 9 Ton, Motion Comfort=46.72
Hinckley 38, Motion Comfort=37.9
Hinckley Bermuda 40, Motion Comfort=35.57
Hinckley Pilot 35 Sloop, Motion Comfort=36.58
Hinckley Sou Wester 51, Sloop, Motion Comfort=44.91
Hinckley Sou'wester 42, Yawl, Motion Comfort=36.21
Hood No Compromise 54 (sloop), Motion Comfort=37.1
Hout Bay 30 Gaff Cutter, Motion Comfort=37.97
Hughes Columbia 391, Motion Comfort=38.89
Hustu 70, Motion Comfort=49.29
Hylas 54, Motion Comfort=38.79
Irwin 37 Mk V, Motion Comfort=36.93
Irwin 46 Ketch, Motion Comfort=39.53
Irwin 52, Motion Comfort=47.6
Irwin 65 Ketch, Motion Comfort=46.75
Island Packet 45, Motion Comfort=35.29
Island Packet 485, Motion Comfort=35.6
Island Trader 36, Motion Comfort=35.16
Islander 44, Motion Comfort=39.56
Jason 35, Motion Comfort=35.03
Kelly Peterson 46, Motion Comfort=38.18
Kettenburg PCC, Motion Comfort=39.38
Knutson 35, Motion Comfort=35.74
Landfall 39 (Sino Amer.), Motion Comfort=42.14
Laurent Guiles Vertue, Motion Comfort=46.91
Lecomte Northeast 38, Motion Comfort=36.12
Liberty 49, Motion Comfort=43.07
Little Harbor 44, Motion Comfort=42.43
Lord Nelson 33, Motion Comfort=35.55
Lord Nelson 35, Motion Comfort=35.86
Lyle Hess 32, Motion Comfort=35.26
MacNaughton Passagemaker, Motion Comfort=42.55
Malo 41, Motion Comfort=38.13
Mariner 35, Motion Comfort=42.3
Mariner 39 C-cockpit, Motion Comfort=38.46
Mariner 40, Motion Comfort=47.22
Mariner 47 (Cruising Version), Motion Comfort=45.55
Mariner Ketch 36, Motion Comfort=43.44
Mason 44, Motion Comfort=41.87
Morgan 37OI MKII Sloop, Motion Comfort=36.84
Morgan 45 Ketch, Motion Comfort=35.19
Morgan 462 Sloop (1981), Motion Comfort=35.15
Morgan 462(1979), Motion Comfort=42.04
Morgan 512, Motion Comfort=43.82
Nauticat 331, Motion Comfort=35.36
Nauticat 44, Motion Comfort=43.69
Navy 44, Motion Comfort=39.62
New York 46 (Roberts), Motion Comfort=48.23
Nicholson 31, Motion Comfort=38.72
Nicholson 33, Motion Comfort=36.59
Nicholson 35, Motion Comfort=36.14
Norseman 447, Motion Comfort=35.61
Ohlson 41 Steel, Motion Comfort=43.85
Passoa 47, Motion Comfort=35.54
Passport 47+3, Motion Comfort=37.84
Pearson 385, Motion Comfort=37.22
Pearson 40, Motion Comfort=35.73
Pearson 43 (1968-72), Motion Comfort=46.38
Pearson Invicta Mark II, Motion Comfort=40.08
Peterson 44, Motion Comfort=37.92
Quoddy Pilot, Motion Comfort=38.98
Rafiki 35, Motion Comfort=36.69
Rawson 30, Motion Comfort=40.12
Reliance, Motion Comfort=53.47
Rhodes Bounty II, Motion Comfort=40.8
Rhodes Reliant, Motion Comfort=44.95
Roberts 28 - Steel, Motion Comfort=37.66
Roberts 35 Cutter, Motion Comfort=38.21
Roberts 420 (cat-ketch), Motion Comfort=41.28
Roberts 45 Pilothouse C. C., Motion Comfort=39.65
Roberts 470, Motion Comfort=37.49
Roberts 53 Aluminum, Motion Comfort=35.57
Roberts 53 Steel Ketch, Motion Comfort=40.77
Roberts 55 Cutter, Motion Comfort=48.98
Roberts 58, Motion Comfort=42.83
Rossiter Curlew, Motion Comfort=37.61
Rossiter Pintail (27 F), Motion Comfort=39.97
Rustler 36, Motion Comfort=35.88
Sailmaster 56 MS, Motion Comfort=49.97
Sea Trader, Motion Comfort=35.59
Seafarer 31 Yawl, Motion Comfort=35.09
Seafarer 34, Motion Comfort=37.08
Seafarer 38 Ketch, Motion Comfort=37.27
Shamrock III, Motion Comfort=52.49
Skye 51, Motion Comfort=43.22
Slocum 43 Cutter, Motion Comfort=37.73
South Coast One Design (C&N), Motion Comfort=46.27
Southern Cross 31, Motion Comfort=38.8
Souwester 51, Motion Comfort=43.84
Sovereign 30, Motion Comfort=43.38
Spencer 44, Motion Comfort=39.76
Spencer 53, Motion Comfort=35.31
Spray 38 Centennial (Roberts), Motion Comfort=46.39
Spray 45 Centennial (Roberts), Motion Comfort=47.35
Stellar 53, Motion Comfort=40.71
Stevens Custom 40, Motion Comfort=37.16
Swallowcraft Scylla, Motion Comfort=36.87
Swan 36, Motion Comfort=37.64
Swan 48, Motion Comfort=42.16
Swan 57 CB Sloop, Motion Comfort=39.42
Tahitiana 32, Motion Comfort=49.38
Talbot 48, Motion Comfort=48.61
Tanton 43, Motion Comfort=38.34
Tashiba 36, Motion Comfort=36.28
Tashiba 40, Motion Comfort=41.25
Tayana 37 Cutter, Motion Comfort=40.78
Tayana 48' Deck Saloon, Motion Comfort=35.77
Tayana 52, Motion Comfort=35.57
Tayana 55, Motion Comfort=37.66
Tayana V-42, Motion Comfort=43.33
Tayana V-42 MKII, Motion Comfort=45.35
Tayana Vancouver 460, Motion Comfort=51.33
True North 34, Motion Comfort=45.92
UWB 333, Motion Comfort=41.15
Union Polaris 36, Motion Comfort=40.06
Vagabond 39PH, Motion Comfort=42
Vagabond 42, Motion Comfort=43.43
Vagabond 47, Motion Comfort=48.71
Valiant 50, Motion Comfort=37.95
Van De Stadt 40 (1954), Motion Comfort=38.41
Waterline 50, Motion Comfort=41.14
Watkins 36, Motion Comfort=36.58
Wauqiez Hood 38, Motion Comfort=38.14
Westsail 28, Motion Comfort=41.08
Westsail 32, Motion Comfort=43.61
Westsail 42 Cutter, Motion Comfort=44.6
Westsail 42 Ketch, Motion Comfort=44.6
Willard 8-ton Cutter, Motion Comfort=40.27
Young Sun 35, Motion Comfort=36.09
Young Sun 43 PH, Motion Comfort=43.13
Zinnia, Motion Comfort=48.48


Any comments guys?

Best winds

And these are the others sailboats, they´re made off by another form, Faster? maybe but not much comfortable. They can cross the Atlantic in a few days to East in comparison with another models, but the crew will suffer seasickness with all the probabilities with bad conditions.

2001 Dehler 39, Motion Comfort=22.28
2004 Dehler 34, Motion Comfort=20.81
A13M, Motion Comfort=24.62
Adams 13m, Motion Comfort=24.62
Adams 31, Motion Comfort=24.16
Aerodyne 47, Motion Comfort=25.82
Airturbine 1967 Model 009, Motion Comfort=29.89
Ajax 28, Motion Comfort=20.72
Albacore 960, Motion Comfort=24.99
Alberg 22, Motion Comfort=20.33
Alberg 29, Motion Comfort=29.67
Albin 85 Cumulus, Motion Comfort=25.93
Albin Ballad, Motion Comfort=21.48
Albin Stratus, Motion Comfort=24.85
Albin Vega, Motion Comfort=20.12
Alerion Express 28, Motion Comfort=21.89
Alerion Express 37, Motion Comfort=22.1
Allegra 24, Motion Comfort=28.54
Allegro 27, Motion Comfort=21.84
Allied Greenwich 24, Motion Comfort=21.54
Allmand 31, Motion Comfort=26.84
Allmand 31, Motion Comfort=23.63
Allmand 35 Pilothouse (1981), Motion Comfort=28.06
Alo 96, Motion Comfort=20.06
Aloha 28, Motion Comfort=20.43
Aloha 32, Motion Comfort=23.12
Aloha 34, Motion Comfort=22.38
Aloha 34 [198*], Motion Comfort=27.18
Aloha 34 [Shoal], Motion Comfort=28.18
American 8.5, Motion Comfort=23.84
Aphrodite 101, Motion Comfort=21.71
Apollo 12, Motion Comfort=23.94
Archarmbault 40rc, Motion Comfort=20.56
Arion By Sid Herreshoff, Motion Comfort=25.38
Baltic 38DP, Motion Comfort=23.1
Baltic 43, Motion Comfort=24.18
Bandholm 26, Motion Comfort=28.12
Bandholm 35, Motion Comfort=27.96
Banner 41 Sport, Motion Comfort=22.55
Bavaria 30, Motion Comfort=22.44
Bavaria 31, Motion Comfort=20.19
Bavaria 33, Motion Comfort=22.89
Bavaria 35, Motion Comfort=26.26
Bavaria 35 Match, Motion Comfort=23.46
Bavaria 38, Motion Comfort=24.2
Bavaria 38 (03) FMain, Motion Comfort=23.36
Bavaria 40, Motion Comfort=22.92
Bavaria 42 (Aft-Furling), Motion Comfort=23.7
Bavaria 47, Motion Comfort=25.65
Bavaria Ocean 42 (CC Furling), Motion Comfort=26.41
Bavaria Ocean 42 (CC), Motion Comfort=26.41
Bayfield 25 Modified +1200#+20%sa, Motion Comfort=21.25
Bayfield 29C 1981, Motion Comfort=20.75
Bayfield 32, Motion Comfort=24.83
Bayfield 32c, Motion Comfort=25.96
Bayliner Buccaneer 240, Motion Comfort=20.21
Bayliner Buccaneer 27, Motion Comfort=25.56
Beneteau 321, Motion Comfort=21.46
Beneteau 331, Motion Comfort=21.46
Beneteau 343, Motion Comfort=22.78
Beneteau 36.7, Motion Comfort=23.61
Beneteau 361, Motion Comfort=20.51
Beneteau 373, Motion Comfort=23.07
Beneteau 393, Motion Comfort=23.8
Beneteau 411, Motion Comfort=22.92
Beneteau 423, Motion Comfort=24.65
Beneteau 42CC, Motion Comfort=26.07
Beneteau 42s 7, Motion Comfort=22.78
Beneteau 45f5 (tall Rig), Motion Comfort=26.09
Beneteau 47.7, Motion Comfort=24.78
Beneteau 473, Motion Comfort=24.34
Beneteau 473 IJPE SA, Motion Comfort=24.34
Beneteau First 30, Motion Comfort=21.6
Beneteau First 32s5, Motion Comfort=22.72
Beneteau First 33.6 Deep Keel, Motion Comfort=22.19
Beneteau First 337, Motion Comfort=22.19
Beneteau First 345, Motion Comfort=28.4
Beneteau First 35s5, Motion Comfort=21
Beneteau First 36.7, Motion Comfort=23.98
Beneteau First 38, Motion Comfort=24.07
Beneteau First 40.7, Motion Comfort=22.92
Beneteau First 405(1986), Motion Comfort=29.29
Beneteau First 41S5, Motion Comfort=22.75
Beneteau First 42, Motion Comfort=23.79
Beneteau First 42 TM, Motion Comfort=23.94
Beneteau First 42s7 (std Rig), Motion Comfort=23.11
Beneteau First 44.7, Motion Comfort=27.51
Beneteau First 44.7 (corrected), Motion Comfort=27.25
Beneteau Idylle 11.50, Motion Comfort=25.92
Beneteau Oceanis 320, Motion Comfort=22.22
Beneteau Oceanis 350, Motion Comfort=20.83
Beneteau Oceanis 36 CC, Motion Comfort=21.7
Beneteau Oceanis 361, Motion Comfort=20.75
Beneteau Oceanis 381, Motion Comfort=20.59
Beneteau Oceanis 390, Motion Comfort=21.06
Beneteau Oceanis 393, Motion Comfort=23.57
Beneteau Oceanis 40 CC, Motion Comfort=25.77
Beneteau Oceanis 400, Motion Comfort=22.55
Beneteau Oceanis 44 CC, Motion Comfort=24.75
Beneteau Oceanis 440, Motion Comfort=24.11
Beneteau Oceanis 510, Motion Comfort=26.02
Benford 26 Cutter, Motion Comfort=24.5
Benford 34 Badger, Motion Comfort=21.97
Benford 36 Donna, Motion Comfort=26.01
Benford 37.5, Motion Comfort=25.65
Bengel (lm32), Motion Comfort=27.83
Bodega 30, Motion Comfort=26.36
Bolger AS29 No Reacher, Motion Comfort=28.62
Bolger AS29 With Reacher, Motion Comfort=28.62
Bolger Blueberry, Motion Comfort=22.65
Bolger Bright Thread, Motion Comfort=20.71
Bolger Grandpas Pirate Ship, Motion Comfort=20.77
Bolger Jessie Cooper, Motion Comfort=27.96
Bolger Jochems Schooner, Motion Comfort=23.28
Bolger Marina Cruiser, Motion Comfort=23.78
Bolger Presto Cruiser, Motion Comfort=27.98
Bolger Red Zinger, Motion Comfort=21.18
Bolger Scow Schooner, Motion Comfort=26.04
Bolger Superbrick, Motion Comfort=23.19
Bolger Volunteer, Motion Comfort=26.99
Bolger Whalewatcher, Motion Comfort=26.54
Brewer Cape Cod Catboat, Motion Comfort=20.41
Brewer Morgane Le Fay, Motion Comfort=28.84
Brewer Murray 33, Motion Comfort=29.13
Bristol 19 Corinthian, Motion Comfort=21.58
Bristol 24/Sailstar Corsair, Motion Comfort=28.39
Bristol 26 (CB), Motion Comfort=23.75
Bristol 26 (keel), Motion Comfort=23.75
Bristol 27, Motion Comfort=28.87
Bristol 27.7, Motion Comfort=20.89
Bristol 29 (1968 ), Motion Comfort=28.42
Bristol 29.9, Motion Comfort=23.36
Bristol 30, Motion Comfort=27.07
Bristol 31.1, Motion Comfort=29.28
Bristol 33, Motion Comfort=28.3
Bristol 34, Motion Comfort=27.2
Buccaneer 335, Motion Comfort=21.93
Bumerang 32, Motion Comfort=24.73
C & C 33 Mk II, Keel/Centreboard, Motion Comfort=25.43
C& C 33-2, Motion Comfort=22.17
C&C 121 Cruise Ed. Shoal Dr., Motion Comfort=25.72
C&C 121 Cruise Edition Shoal Draft, Motion Comfort=25.72
C&C 29 MKII, Motion Comfort=21.49
C&C 30 1989, Motion Comfort=20.1
C&C 30 Mega, Motion Comfort=26.31
C&C 30 Mk I, Motion Comfort=21.7
C&C 30 Mk II (Wing Keel), Motion Comfort=21.29
C&C 32, Motion Comfort=25.06
C&C 32 (1984), Motion Comfort=24.76
C&C 33 Mark 1, Motion Comfort=23.04
C&C 33 Mark 11, Motion Comfort=23.01
C&C 33mk1 1986, Motion Comfort=24.75
C&C 34, Motion Comfort=22.55
C&C 35, Motion Comfort=22.74
C&C 35 MK I, Motion Comfort=23.47
C&C 35, Mk II, Motion Comfort=28.96
C&C 35-III, Motion Comfort=22.26
C&C 36, Motion Comfort=23.36
C&C 37 (1985), Motion Comfort=26.68
C&C 37+, Motion Comfort=25.35
C&C 37R/40, Motion Comfort=23.05
C&C 38 MK II (1976), Motion Comfort=25.76
C&C 38 MkIII, Motion Comfort=22.12
C&C 39, Motion Comfort=29.52
C&C 40, Motion Comfort=25.9
C&C 40 C/B, Motion Comfort=27.64
C&C 41, Motion Comfort=26.74
C&C Corvette, Motion Comfort=28.01
C&C Frigate 36, Motion Comfort=28.92
C&C Landfall 35, Motion Comfort=29.17
C&C Landfall 38, Motion Comfort=27.29
C&C Redwing 30, Motion Comfort=26.02
C&amp; C 33-2, Motion Comfort=22.17
CF 37, Motion Comfort=21.77
CR 310, Motion Comfort=23.47
CS 27 (Shoal), Motion Comfort=20.49
CS 30, Motion Comfort=20.63
CS 33, Motion Comfort=22.85
CS 34, Motion Comfort=21.78
CS 36M, Motion Comfort=24.29
CS 40, Motion Comfort=25.56
CS36T (deep Keel), Motion Comfort=29.23
CS36T (shoal), Motion Comfort=29.23
Cal 2-27, Motion Comfort=22.66
Cal 2-29, Motion Comfort=24.79
Cal 28, Motion Comfort=20.42
Cal 29, Motion Comfort=24.86
Cal 3-30, Motion Comfort=25.62
Cal 31, Motion Comfort=23.9
Cal 33, Motion Comfort=23
Cal 33 (shoal), Motion Comfort=23.43
Cal 34, Motion Comfort=24.06
Cal 35 MkII, Motion Comfort=25.91
Cal 39, Motion Comfort=27.54
Cal 39TM (cira 70)MK Cutter, Motion Comfort=24.92
Cal 40, Motion Comfort=29.51
Cal Cruising 36, Motion Comfort=28
Cal-30, Motion Comfort=22.39
Caliber 33, Motion Comfort=25.85
Caliber 35, Motion Comfort=25.06
Cape Dory 25, Motion Comfort=21.87
Cape Dory 25D, Motion Comfort=23.67
Cape Dory 26, Motion Comfort=23.99
Cape Dory 270, Motion Comfort=28.63
Cape Dory 30 MKII, Motion Comfort=26.97
Cape Dory 300 Motorsailor, Motion Comfort=24.68
Caribbea, Motion Comfort=22.41
Cascade 27, Motion Comfort=23.3
Cascade 36, Motion Comfort=29.87
Cascade 44, Motion Comfort=28.76
Cascade Sloop, Motion Comfort=26.98
Catalina 27 Std Rig, Motion Comfort=24.03
Catalina 27 Tall Rig DK OB, Motion Comfort=26.09
Catalina 270, Motion Comfort=20.7
Catalina 28 MkII (SR-fin Keel), Motion Comfort=22.78
Catalina 28 MkII (SR-wing Keel), Motion Comfort=23.6
Catalina 28 MkII (TR-fin Keel), Motion Comfort=22.78
Catalina 28 MkII(TR-wing Keel), Motion Comfort=23.6
Catalina 289, Motion Comfort=24.04
Catalina 30, Motion Comfort=24.71
Catalina 309, Motion Comfort=20.86
Catalina 309 (wing Keel), Motion Comfort=21.71
Catalina 30TRBS, Motion Comfort=24.97
Catalina 310, Motion Comfort=21.85
Catalina 320, Motion Comfort=23.17
Catalina 34 SR/Fin, Motion Comfort=22.05
Catalina 34 Wing Keel, Motion Comfort=23.08
Catalina 350, Motion Comfort=21.12
Catalina 36 MK II TR/Fin Keel, Motion Comfort=23.78
Catalina 36 SR/Fin, Motion Comfort=23.78
Catalina 36 Std Rig Wing, Motion Comfort=24.83
Catalina 36 TR Wing, Motion Comfort=24.89
Catalina 38 (S&S Design), Motion Comfort=28.08
Catalina 400, Motion Comfort=23.61
Catalina 400 Mk II, Motion Comfort=25.77
Catalina 42, Motion Comfort=22.12
Catalina 470 Wing/Std, Motion Comfort=29.09
Centurion 36, Motion Comfort=28.42
Challenger 32, Motion Comfort=26.28
Challenger 41, Motion Comfort=23.1
Chance 32/28, Motion Comfort=29.48
Chris Craft Cherokee 32, Motion Comfort=28.2
Chrysler 26, Motion Comfort=20.73
Columbia 10.7, Motion Comfort=28.82
Columbia 26, Motion Comfort=23.61
Columbia 26 MKII Shoal Keel, Motion Comfort=25.55
Columbia 26MKII, Motion Comfort=23.03
Columbia 28, Motion Comfort=24.59
Columbia 28 MKII, Motion Comfort=25.62
Columbia 30, Motion Comfort=29.12
Columbia 31, Motion Comfort=25.5
Columbia 34, Motion Comfort=29.36
Columbia 36, Motion Comfort=26.37
Columbia 8.3, Motion Comfort=24.83
Columbia 8.7, Motion Comfort=24.48
Columbia 9.6, Motion Comfort=28.15
Columbia Sabre, Motion Comfort=27.22
Colvic Countess 33, Motion Comfort=28.74
Com-Pac 35, Motion Comfort=22.6
Comar Comet 1050, Motion Comfort=22.12
Compass 29, Motion Comfort=26.11
Compromis 34 ( C Yacht 10.40) (NL), Motion Comfort=24.82
Compromis 36, Motion Comfort=26.82
Compromis 999 (NL), Motion Comfort=23.66
Contention 33, Motion Comfort=22.24
Contessa 26, Motion Comfort=25.33
Contessa 32, Motion Comfort=27.84
Contest 31 HTB, Motion Comfort=26.6
Contest 33, Motion Comfort=28.47
Contest 36, Motion Comfort=28.59
Cornish Crabber Piper 24, Motion Comfort=25.44
Coronado 27, Motion Comfort=23.66
Coronado 28, Motion Comfort=26.11
Coronado 30, Motion Comfort=23.3
Crown 28, Motion Comfort=22.91
Crown 34, Motion Comfort=22.27
Degero 28, Motion Comfort=22.17
Degero 28 MS, Motion Comfort=22.17
Dehler 34, Motion Comfort=20.95
Delta 36, Motion Comfort=22.43
Dickerson 35, Motion Comfort=27.79
Down East Schooner, Motion Comfort=21.93
Dufour 2800, Motion Comfort=20.21
Dufour 31, Motion Comfort=25.76
Dufour 35, Motion Comfort=20.25
Dufour 36 Classic, Motion Comfort=21.97
Dufour 365, Motion Comfort=23.78
Dufour 38, Motion Comfort=21.65
Dufour 385, Motion Comfort=23.59
Dufour 39 CC, Motion Comfort=26.57
Dufour 40, Motion Comfort=22.51
Dufour 43 CC, Motion Comfort=22.71
Dufour 44, Motion Comfort=25.89
Dufour 45 Classic, Motion Comfort=27.13
Dufour Arpege, Motion Comfort=23.83
ELAN 340, Motion Comfort=21
ELAN IMPRESSION 344, Motion Comfort=26.27
Easterly 30, Motion Comfort=22.56
Elan 333, Motion Comfort=23.1
Elan 36, Motion Comfort=22.74
Elan 37, Motion Comfort=24.43
Elan 40, Motion Comfort=23.65
Elan E36 1997, Motion Comfort=21.77
Elan Impression 344, Motion Comfort=23.72
Elan Impression 384, Motion Comfort=23.07
Elite 32, Motion Comfort=21.07
Endeavour 33, Motion Comfort=23.48
Endeavour 35, Motion Comfort=23.28
Ericson (Pacific Seacraft), Motion Comfort=26.59
Ericson 25, Motion Comfort=23.66
Ericson 27, Motion Comfort=25.61
Ericson 28+, Motion Comfort=22.36
Ericson 29, Motion Comfort=28.09
Ericson 30+, Motion Comfort=22.58
Ericson 30-1, Motion Comfort=21.91
Ericson 31i, Motion Comfort=29.89
Ericson 32, Motion Comfort=26.11
Ericson 32 MKII (1986), Motion Comfort=22.61
Ericson 32-200, Motion Comfort=22.62
Ericson 32-Mk3, Motion Comfort=21.79
Ericson 33, Motion Comfort=20.26
Ericson 34, Motion Comfort=25.57
Ericson 35 II, Motion Comfort=29.14
Ericson 35 MKIII, Motion Comfort=25.77
Ericson 36C, Motion Comfort=28.2
Ericson 38 (80-83?), Motion Comfort=25.56
Ericson 38 (very Early), Motion Comfort=24.01
Ericson 38-200, Motion Comfort=26.59
Ericson 381, Motion Comfort=24.7
Etap 30, Motion Comfort=20.52
Etap 37s, Motion Comfort=22.03
Express 30, Motion Comfort=22.39
Express 35, Motion Comfort=27.9
Facil 355 XO, Motion Comfort=22.31
Farallon 29, Motion Comfort=26.54
Farr 1220, Motion Comfort=21.66
Farr 37, Motion Comfort=20.87
Feeling 36, Motion Comfort=24.15
Folkboat, Motion Comfort=22.37
Fortune 30, Motion Comfort=26.09
Freedom 33, Motion Comfort=24.42
Freedom 35, Motion Comfort=25.98
Freedom 36, Motion Comfort=24.48
Freedom 38, Motion Comfort=23.45
Freedom Ph39, Motion Comfort=28.07
Frers 38 (Carroll Marine), Motion Comfort=22.44
Frers 38 (New Orleans Marine), Motion Comfort=21.89
Frers 41, Motion Comfort=22.7
Garcia CC 48, Motion Comfort=28.21
Genzel Phantom, Motion Comfort=22.02
Genzel Phantom 30, Motion Comfort=26.33
Gib Sea 33, Motion Comfort=22.35
Gib Sea 37, Motion Comfort=22.47
Gib'Sea 41, Motion Comfort=23.5
Glen-L 30, Motion Comfort=28.45
Glen-L Amigo, Motion Comfort=23.44
Glen-L Coaster, Motion Comfort=21.86
Glen-L Delphin 36, Motion Comfort=29.06
Glen-L Francis Drake, Motion Comfort=28.64
Glen-L James Cook, Motion Comfort=23.51
Gozzard 31, Motion Comfort=26.02
Grampian 2-34, Motion Comfort=28.83
Grampian 26, Motion Comfort=21.81
Grampian 28, Motion Comfort=20.65
Grampian 30, Motion Comfort=24.56
Grand Soleil 40, Motion Comfort=21.88
Grand Soleil 46.3, Motion Comfort=25.82
Gulf 29, Motion Comfort=21.58
Gulfstar 44, Motion Comfort=27.82
HR 28, Motion Comfort=26.27
Halcyon 27, Motion Comfort=29.59
Hallberg Rassy 35, Motion Comfort=29.12
Hallberg Rassy 94 Kutter, Motion Comfort=26.71
Hallberg Rassy Rasmus 35, Motion Comfort=29.2
Hallberg-Rassy 29, Motion Comfort=25.89
Hallberg-Rassy 31 Mk II, Motion Comfort=22.4
Hallberg-Rassy 34, Motion Comfort=23.71
Hallberg-Rassy 342, Motion Comfort=22.93
Hallberg-Rassy 36, Motion Comfort=29.49
Hallberg-Rassy 37, Motion Comfort=28.43
Hallberg-Rassy 37, Motion Comfort=27.72
Hallberg-Rassy HR31, Motion Comfort=21.56
Hallberg-Rassy Monsun 31, Motion Comfort=26.68
Hallman 27, Motion Comfort=24.03
Hanse 311, Motion Comfort=20.42
Hanse 320, Motion Comfort=23
Hanse 350, Motion Comfort=28.48
Hanse 370, Motion Comfort=23.76
Hanse 371, Motion Comfort=22.21
Hanse 461, Motion Comfort=26.41
Harstad 32 Motorsailor, Motion Comfort=27.7
Helms 32, Motion Comfort=24.38
Heritage West Indies 36, Motion Comfort=28.58
Herreschoff H-28, Motion Comfort=23.85
Herreshoff 45 Cat Ketch, Motion Comfort=21.34
Herreshoff Meadow Lark, Motion Comfort=23.59
Hoyt 28, Motion Comfort=28.35
Hughes 38, Motion Comfort=28.14
Hugues 29 (1972), Motion Comfort=24.43
Hullmaster 27, Motion Comfort=25.24
Hunter 25, Motion Comfort=21.35
Hunter 27 (1975-1984), Motion Comfort=23.55
Hunter 27 (2005), Motion Comfort=21.98
Hunter 27 Shoal (1976), Motion Comfort=24.22
Hunter 30 (early), Motion Comfort=25.39
Hunter 30-2, Motion Comfort=22.04
Hunter 31, Motion Comfort=22.72
Hunter 31 (1983-7), Motion Comfort=22.21
Hunter 320, Motion Comfort=20.5
Hunter 33, Motion Comfort=25.64
Hunter 33 Furling, Motion Comfort=20.08
Hunter 33 Henderson, Motion Comfort=21.37
Hunter 33.5, Motion Comfort=23.11
Hunter 34 DK, Motion Comfort=23.06
Hunter 34 SD, Motion Comfort=23.25
Hunter 340, Motion Comfort=21.34
Hunter 35 (bulb Wing Keel 87-89), Motion Comfort=23.03
Hunter 35 (fin Keel 87-89), Motion Comfort=22.67
Hunter 35.5, Motion Comfort=23.05
Hunter 356, Motion Comfort=24.28
Hunter 36 (1980-82), Motion Comfort=26.76
Hunter 37 (86 89), Motion Comfort=23
Hunter 37.5, Motion Comfort=25.09
Hunter 376, Motion Comfort=24.84
Hunter 38, Motion Comfort=26.24
Hunter 380, Motion Comfort=23.57
Hunter 40, Motion Comfort=24.97
Hunter 40 DK, Motion Comfort=24.24
Hunter 40.5 Bulb Wing Keel, Motion Comfort=26.23
Hunter 41, Motion Comfort=25.57
Hunter 410 (Deep), Motion Comfort=23.29
Hunter 410 (Shoal), Motion Comfort=24.12
Hunter 42, Motion Comfort=28.17
Hunter 426, Motion Comfort=25.75
Hunter 430, Motion Comfort=27.59
Hunter 450, Motion Comfort=29.43
Hunter 466, Motion Comfort=28.7
Hunter 49, Motion Comfort=29.72
Hunter 54, Motion Comfort=26.46
Hunter HS470, Motion Comfort=29.09
Hunter Legend 35 DK, Motion Comfort=22.67
Hunter Legend 45 DK, Motion Comfort=28.11
Hunter Mystery 35, Motion Comfort=25.98
Hunter Passage 420, Motion Comfort=24.07
Hunter Vision 32, Motion Comfort=23.19
Hunter Vision 36, Motion Comfort=25.79
Hurley 22, Motion Comfort=23.11
Hylas 44, Motion Comfort=26.82
Intrepid 28, Motion Comfort=22.45
Irwin 10/4, Motion Comfort=21.03
Irwin 28, Motion Comfort=24.28
Irwin 30, Motion Comfort=26.52
Irwin Citation 34, Motion Comfort=23.77
Irwin Citation 35.5, Motion Comfort=22.27
Irwin Mk 2, Motion Comfort=26.49
Island Packet 27, Motion Comfort=20.61
Island Packet 29, Motion Comfort=24.21
Island Packet 31, Motion Comfort=21.93
Island Packet 32, Motion Comfort=26.95
Island Packet 320, Motion Comfort=26.93
Island Packet 350, Motion Comfort=29.89
Islander 28, Motion Comfort=20.93
Islander 29 (1969), Motion Comfort=27.61
Islander 30 Mk II, Motion Comfort=23.48
Islander 32 (1977), Motion Comfort=23.93
Islander 32 Mk II TR (1979), Motion Comfort=24.15
Islander 36, Motion Comfort=27.11
Islander 37, Motion Comfort=29.2
Islander Bahama 30, Motion Comfort=22.45
Islander P40, Motion Comfort=29.01
J/110, Motion Comfort=23.63
J/120, Motion Comfort=21.33
J/124, Motion Comfort=20.29
J/145, Motion Comfort=21.66
J/28, Motion Comfort=22.25
J/32, Motion Comfort=21.93
J/32c, Motion Comfort=20.97
J/37, Motion Comfort=21.51
J/40, Motion Comfort=25.81
J/42, Motion Comfort=29.03
J/44, Motion Comfort=25.08
J122, Motion Comfort=23.27
J34c, Motion Comfort=23.78
J35c, Motion Comfort=23.23
Jeanneau 36i, Motion Comfort=21.3
Jeanneau Espace 900, Motion Comfort=24.62
Jeanneau SF37, Motion Comfort=23.13
Jeanneau Sun Dance, Motion Comfort=23.3
Jeanneau Sun Fast 35, Motion Comfort=21.88
Jeanneau Sun Fast 37, Motion Comfort=23.13
Jeanneau Sun Fast 39, Motion Comfort=21.12
Jeanneau Sun Fizz 40, Motion Comfort=26.56
Jeanneau Sun Odyssey 32, Motion Comfort=22.62
Jeanneau Sun Odyssey 33, Motion Comfort=21.4
Jeanneau Sun Odyssey 34.2, Motion Comfort=21.6
Jeanneau Sun Odyssey 35, Motion Comfort=21.52
Jeanneau Sun Odyssey 36.2, Motion Comfort=20.33
Jeanneau Sun Odyssey 37, Motion Comfort=21.08
Jeanneau Sun Odyssey 37.2, Motion Comfort=20.48
Jeanneau Sun Odyssey 40, Motion Comfort=25.2
Jeanneau Sun Odyssey 40.3, Motion Comfort=27.77
Jeanneau Sun Odyssey 43, Motion Comfort=24.63
Jeanneau Sun Odyssey 43DS, Motion Comfort=24.27
Jeanneau Sun Odyssey 45 Performance, Motion Comfort=24.02
Jeanneau Sun Odyssey 45.2, Motion Comfort=21.29
Jeanneau Sun Odyssey 49, Motion Comfort=27.73
Jeanneau SunRise 34, Motion Comfort=20.51
Jeanneau Sunkiss 45, Motion Comfort=28.06
Joker 820, Motion Comfort=20.68
Kalik 44, Motion Comfort=29.51
Kenner Privateer 26, Motion Comfort=25.87
Kettenberg 32, Motion Comfort=27.86
Kittiwake 23, Motion Comfort=20.17
LM Glasfiber 30, Motion Comfort=29.22
LM Glasfiber 32, Motion Comfort=29.43
LT36 (Andersen Lateen Sloop), Motion Comfort=27.29
Lancer 29 Mk II, Motion Comfort=22.21
Lancer 30, Motion Comfort=22.72
Lapworth Gladiator, Motion Comfort=22.24
Laurin 28, Motion Comfort=27.05
Lippincott 30, Motion Comfort=23.11
Long Micro, Motion Comfort=20.08
Luders 16, Motion Comfort=24.76
Luger Voyager 30, Motion Comfort=24.48
MacGregor 65, Motion Comfort=28.18
Mariner 28, Motion Comfort=23.63
Matt Layden Paradox, Motion Comfort=24.89
Maxi 1050, Motion Comfort=22.27
Midget 31, Motion Comfort=23.09
Mirage 275, Motion Comfort=20.63
Mirage 30, Motion Comfort=20.41
Mirage 39, Motion Comfort=24.32
Miura 30, Motion Comfort=25.84
Moody 33, Motion Comfort=20.89
Moody 35, Motion Comfort=24.03
Moody 38, Motion Comfort=29.17
Morgan 24 1965-68 Keel-CB, Motion Comfort=21.8
Morgan 25 (1976), Motion Comfort=21.35
Morgan 27 MORC, Motion Comfort=21.08
Morgan 28, Motion Comfort=25.02
Morgan 28 OI, Motion Comfort=25.16
Morgan 30 OI, Motion Comfort=28.93
Morgan 30/2, Motion Comfort=21.44
Morgan 323, Motion Comfort=24.06
Morgan 33 OI, Motion Comfort=28.41
Morgan 35, Motion Comfort=25.92
Morgan 38, Motion Comfort=28.33
Morgan 43 (N-M Design), Motion Comfort=29.9
Morgan 44, Motion Comfort=29.64
Morgan 45 (N-M Design), Motion Comfort=25.04
Morgan 45 (N-M Design), Motion Comfort=27.37
Morgan Classic 41(1987), Motion Comfort=29.46
Morris 26, Motion Comfort=28.06
Morris 28, Motion Comfort=27.02
Morris 32, Motion Comfort=28.38
Morris 34, Motion Comfort=27.15
Morris 36, Motion Comfort=29.1
Morris 38, Motion Comfort=28.68
Morris 40, Motion Comfort=28.84
Morris Leigh 30, Motion Comfort=27.27
Mystic 10-3, Motion Comfort=22.05
Najad 355, Motion Comfort=26.16
Najade 900, Motion Comfort=23.32
Najade 900a, Motion Comfort=23.29
Nautilus 40, Motion Comfort=29.77
New Horizon, Motion Comfort=26.83
Newbridge Pioneer, Motion Comfort=23.75
Newport 27, Motion Comfort=20.35
Newport 28, Motion Comfort=20.67
Newport 28 MKII, Motion Comfort=20.72
Newport 30 MK II, Motion Comfort=20.2
Newport 33, Motion Comfort=21.13
Niagara 31, Motion Comfort=22.06
Nimble Wanderer MS, Motion Comfort=27.75
Nonsuch 26, Motion Comfort=22.98
Nonsuch 30, Motion Comfort=22.46
Nonsuch 324, Motion Comfort=22.03
Nonsuch 36, Motion Comfort=25.72
Nor' Sea 26 Pilot House, Motion Comfort=23.81
Nordic 40, Motion Comfort=27.79
Nordica 30, Motion Comfort=28.57
Northern 25 Mk 1&2, Motion Comfort=22.19
Northern 25 Mk 3, Motion Comfort=22.65
Northern 29, Motion Comfort=24.51
Northsea 34 Pilothouse, Motion Comfort=26.8
Northshore 46, Motion Comfort=26.19
Northwest 21, Motion Comfort=21.92
Northwest 28, Motion Comfort=25.06
Nova 28, Motion Comfort=21.48
O'Day 26, Motion Comfort=20.1
O'Day 31, Motion Comfort=24.3
ODay 25, Motion Comfort=20.89
ODay 25 C/B, Motion Comfort=20.87
ODay 27, Motion Comfort=23.77
ODay 28, Motion Comfort=20.57
ODay 28 1979, Motion Comfort=21.18
ODay 30, Motion Comfort=24.59
ODay 322, Motion Comfort=23.71
ODay 34/35, Motion Comfort=22.94
ODay 37, Motion Comfort=26.75
ODay 39, Motion Comfort=26.82
ODay 40, Motion Comfort=26.59
Ocean 31 Lavranos, Motion Comfort=20.67
Oceanis 49, Motion Comfort=25.86
Oday 32 Center Cockpit, Motion Comfort=25.8
Oday 34, Motion Comfort=23.15
Olson 34, Motion Comfort=22.64
Olympic Star 23, Motion Comfort=20.92
Omega 36, Motion Comfort=22.23
Ontario 28, Motion Comfort=20.22
Ontario 32, Motion Comfort=21.89
Ovni 345, Motion Comfort=27.42
Oyster 37, Motion Comfort=24.25
Paceship 26, Motion Comfort=20.05
Paceship 29 Northwind, Motion Comfort=22.09
Paceship Eastwind 25, Motion Comfort=23.81
Paceship Westwind, Motion Comfort=22.38
Pacific Dolphin 24, Motion Comfort=21.04
Pacific Seacraft 24, Motion Comfort=29.59
Pacific Seacraft 25, Motion Comfort=20.71
Paine Sarah 32, Motion Comfort=29.14
Parker 275, Motion Comfort=22.04
Parker 335, Motion Comfort=20.85
Passoa 54, Motion Comfort=29.23
Pearson 10M, Motion Comfort=26.43
Pearson 24, Motion Comfort=20.67
Pearson 26, Motion Comfort=20.2
Pearson 28-1 75-82, Motion Comfort=24.69
Pearson 28-2 85-89 SD, Motion Comfort=21.04
Pearson 30, Motion Comfort=24.06
Pearson 303, Motion Comfort=24.51
Pearson 31 MK 2 (Deep), Motion Comfort=23.87
Pearson 31 MK 2 (Wing), Motion Comfort=24.35
Pearson 31-II WK, Motion Comfort=24.45
Pearson 32, Motion Comfort=22.99
Pearson 33 (1969-80), Motion Comfort=27.96
Pearson 33-2, Motion Comfort=24.6
Pearson 34 (1983), Motion Comfort=23.22
Pearson 36, Motion Comfort=23.73
Pearson 36-2, Motion Comfort=25.69
Pearson 37-2, Motion Comfort=27.14
Pearson 38, Motion Comfort=25.65
Pearson 39 C/B, Motion Comfort=27.88
Pearson 39-2, 1986 - 1991, Motion Comfort=28.43
Pearson 390, Motion Comfort=29.32
Pearson 424, Motion Comfort=29.05
Pearson Ariel, Motion Comfort=23.86
Pearson Coaster, Motion Comfort=29.61
Pearson Coaster, Motion Comfort=29.17
Pearson Coaster, Motion Comfort=29.84
Pearson Commander, Motion Comfort=24.8
Pearson Renegade 27, Motion Comfort=24.84
Pearson Triton 28, Motion Comfort=27.97
Peterson 33, Motion Comfort=21.93
Peterson 34(1979), Motion Comfort=22.01
Peterson 35, Motion Comfort=26.35
Precision Seaforth 24, Motion Comfort=22.96
Radford 14, Motion Comfort=27.84
Ranger 26 Mull Dsgn, Motion Comfort=21.84
Ranger 29, Motion Comfort=21.39
Ranger 33, Motion Comfort=28.04
Rival-Bowman 40, Motion Comfort=29.05
Riviera Star 316, Motion Comfort=23.12
Roberts 25 Pilothouse, Motion Comfort=20.22
Rodgers 28, Motion Comfort=23.74
Rommel 34 CR, Motion Comfort=21.16
Rutu(custom), Motion Comfort=27.47
S2 10.3, Motion Comfort=21.35
S2 11, Motion Comfort=27.79
S2 35C, Motion Comfort=27.31
S2 8.5, Motion Comfort=23.66
S2 9.2A, Motion Comfort=25.55
SAS Vektor 36, Motion Comfort=20.52
Sabre 27, Motion Comfort=24.94
Sabre 28, Motion Comfort=25.84
Sabre 28 Series I, Motion Comfort=24.74
Sabre 28 Series III, Motion Comfort=25.92
Sabre 30 Mk II, Motion Comfort=23.83
Sabre 30-3, Motion Comfort=23.79
Sabre 32, Motion Comfort=25.12
Sabre 32 (K/CB), Motion Comfort=25.84
Sabre 34, Motion Comfort=27.49
Sabre 34 MK I, Motion Comfort=26.79
Sabre 34 Targa, Motion Comfort=23.6
Sabre 362 (CB), Motion Comfort=26.1
Sabre 362 (DK), Motion Comfort=24.04
Sabre 362 (WK), Motion Comfort=25.45
Sabre 38 II, Motion Comfort=27.81
Sabre 38 MK I, Motion Comfort=27.19
Sabre 386, Motion Comfort=25.06
Sabre 402, Motion Comfort=24.77
Sabre 42, Motion Comfort=27.85
Sadler 29, Motion Comfort=25.58
Sadler 32, Motion Comfort=24.22
Sadler 34, Motion Comfort=27.08
Saga 35, Motion Comfort=24.1
Saga 409, Motion Comfort=28.06
Saga 43, Motion Comfort=28.02
Sailmaster 22 Cruiser 1962, Motion Comfort=22.71
Sailmaster 22c, Motion Comfort=27.99
Sailmaster 26, Motion Comfort=21.63
Salona 37, Motion Comfort=22.07
Sandpiper Sharpie, Motion Comfort=24.4
Santana 30, Motion Comfort=21.58
Sas 39, Motion Comfort=21.11
Scampi MK2, Motion Comfort=21.11
Scanmar 31, Motion Comfort=21.79
Scanmar 33, Motion Comfort=22.65
Scanmar 35, Motion Comfort=22.78
Sceptre 36, Motion Comfort=23.04
Sea Sprite 23, Motion Comfort=21.26
Sea Sprite 27, Motion Comfort=28.63
Seacracker 33, Motion Comfort=26.97
Seafarer 23 (1970), Motion Comfort=20.95
Seafarer 29, Motion Comfort=21.9
Seafarer Meridian, Motion Comfort=29.66
Seafarer Polaris, Motion Comfort=22.29
Seaward Eagle 32, Motion Comfort=20.34
Shannon 28, Motion Comfort=28.99
Shields, Motion Comfort=25.65
Show 34, Motion Comfort=21.28
Sirena 38, Motion Comfort=26.91
Slotta 34 ComfortCcruiser, Motion Comfort=22.8
South Coast 23, Motion Comfort=21.47
Southerly 101, Motion Comfort=24.89
Southerly 110, Motion Comfort=27.38
Sparhawk 36, Motion Comfort=21.47
Spencer 34, Motion Comfort=21.24
Spirit 28, Motion Comfort=20.11
Storebro Royal 33, Motion Comfort=21.15
Sunbeam 34, Motion Comfort=24.19
Sunbird 32 Junk Schooner, Motion Comfort=24.64
Tanton 43 Cat Ketch, Motion Comfort=25.71
Tanzer 10.5, Motion Comfort=26.06
Tanzer 27, Motion Comfort=20.29
Tartan 26, Motion Comfort=21.23
Tartan 27, Motion Comfort=27.85
Tartan 27 (Mark Two), Motion Comfort=27.85
Tartan 28, Motion Comfort=21.93
Tartan 30, Motion Comfort=24.06
Tartan 3000, Motion Comfort=21.08
Tartan 31, Motion Comfort=20.78
Tartan 33, Motion Comfort=21.91
Tartan 34 Scheel Keel (1987), Motion Comfort=22.79
Tartan 34-2, Motion Comfort=22.79
Tartan 34c, Motion Comfort=28.13
Tartan 34c E=13, Motion Comfort=28.13
Tartan 3500, Motion Comfort=24.09
Tartan 37 (K/CB), Motion Comfort=28.97
Tartan 3700, Motion Comfort=24.96
Tartan 372 Scheel, Motion Comfort=25.7
Tartan 40, Motion Comfort=27.1
Tartan 40 Shoal, Motion Comfort=27.32
Tartan 41, Motion Comfort=27.64
Tartan 4100, Motion Comfort=24
Tartan 5100, Motion Comfort=27.83
Temptress 34, Motion Comfort=25.89
Terrapin 34, Motion Comfort=29.01
Ticon 30, Motion Comfort=22.22
Tom Thumb 24, Motion Comfort=26.8
Tom Thumb 26, Motion Comfort=25.25
Tomahawk 25, Motion Comfort=20.81
Top Hat 25, Motion Comfort=26.62
Valiant 32, Motion Comfort=28.36
Van De Stadt 30, Motion Comfort=22.71
Van De Stadt 34, Motion Comfort=22.26
Van De Stadt 40, Motion Comfort=26.12
Vancouver 25, Motion Comfort=28.01
Varne 850, Motion Comfort=22.09
Viking 33, Motion Comfort=22.12
Voyager 26, Motion Comfort=26.95
W-46, Motion Comfort=27.28
W-46, Motion Comfort=27.27
Warrior 35, Motion Comfort=28.64
Wasa, Motion Comfort=20.57
Watkins 25, Motion Comfort=21.04
Watkins 27, Motion Comfort=21.71
Watkins 29, Motion Comfort=23.6
Watkins 32, Motion Comfort=26.56
Watkins 33, Motion Comfort=28.13
Wauquiez 40 Standard, Motion Comfort=26.34
Wauquiez Centurion 40S (shoal), Motion Comfort=23.12
Wauquiez Centurion 45s (std), Motion Comfort=25.79
Wauquiez Gladiateur, Motion Comfort=24.85
Wauquiez Pilot 40, Motion Comfort=28.62
Wauquiez Pretorien, Motion Comfort=24.05
Westerly 36 Corsair, Motion Comfort=25.85
Westerly Berwick 31, Motion Comfort=29.03
Westerly Centaur 26, Motion Comfort=26.21
Westerly Fulmar, Motion Comfort=22.65
Westerly Longbow, Motion Comfort=27.13
Westerly Merlin, Motion Comfort=22.3
Westerly Pageant, Motion Comfort=20.45
Westerly Pentland, Motion Comfort=28.55
Westerly Sealord, Motion Comfort=26.68
Westerly Storm 33' Cruiser, Motion Comfort=25.21
Westerly Tiger 25, Motion Comfort=20.22
Wibo 945, Motion Comfort=28.06
Wylie Cat 39, Motion Comfort=21.45
X-332, Motion Comfort=20.53
X-342, Motion Comfort=20.94
X-412, Motion Comfort=23.82
X-412 Mk III, Motion Comfort=24.16
X-442 MKII, Motion Comfort=26.15
Yamaha 33, Motion Comfort=21.53
Yankee 26, Motion Comfort=20.51
Yankee 30 MK I, Motion Comfort=28.47
Yankee 30 MK II, Motion Comfort=28.52
Yankee Dolphin 24, Motion Comfort=20.6

Best winds

And now, I bring your attention about this:

Transpac 52, Motion Comfort=14.91


Is she faster?

Best winds

And now, I bring your attention about this:

Transpac 52, Motion Comfort=14.91

Longer boats have a more comfortable motion, no big surprise.
I do not think anybody on a TP52 going upwind in a force 7 at maximum speed will describe her motion being as comfortable.

If someone wants to invite me on his TP52 to try this out for myself i will accept the offer happily though.

Hey Antonio! You have done a hell of a job! Well done!

Motion Comfort Ratio provides a good clue to a boat's seakindliness, in addition to the roll acceleration parameter, usually calculated as:
(6.28/T)^2*radius*(10*Pi/180)/32.2
being T the rolling period and 'radius' the radius of inerta. There are approximate formulas to estimate those also, as you probably already know.

Motion Comfort Ratio is only a clue, not an absolute true, but anyhow it indicates what you can expect from a boat. As Ted Brewer puts it:
"Do consider, though, that a sailing yacht heeled by a good breeze will have a much steadier motion than one bobbing up and down in light airs on left over swells from yesterday's blow; also that the typical summertime coastal cruiser will rarely encounter the wind and seas that an ocean going yacht will meet. Nor will one human stomach keep down what another stomach will handle with relish, or with mustard and pickles for that matter! It is all relative."

There is also an study on the effects of acceleration aboard on human performance, done by the US Navy (or was it the Coast Guard?), but I don't have it here now. I'll check tonight and post the curves.

Is it correct such a low MCR for the Transpac 52?

Cheers.

I think a lot depends on ones state of mind. Some people are seasick before they board... like some people itch from working with glass before they even touch the stuff...

Antonio,

Many thanks for taking the effort of posting those very useful figures. -----

Wot!! No Gunboat 62? :D :D Easy to tack, minimum pitching due to gentle, uniform rocker along hulls and with dagger boards raised, she surfs sideways and avoids tripping in a beam sea. That sounds supremely comfortable to me. :D :D

http://www.deltayachtsbrokerage.com/news/YWorld_gb62.pdf

Guillermo,

Close attention was paid to reducing vertical acceleration in the design of Destriero with a view to reducing fatigue. Three hull forms were considered and the smoothest riding was chosen.

http://www.proboat-digital.com/proboat/20071011/

The longer hulled cruising catamarans are quicker under sail than monohulls and seem to slice through waves. This suggests they have lower vertical acceleration than the monos, which have to climb the waves. I am inclined to the view that that ride quality would be another factor in favour of catamarans, as discussed elsewhere on the forum.

http://boatdesign.net/forums/showthread.php?t=4499

It will be interesting to read the conclusions in the American papers you have.

Best wishes to you both.

Perry

from the library i find a whole lot of info in Marchaj; seawhorthiness, the forgotten factor

To Guillermo. Yes it´s right the number as far as i know

To Fanie. I don´t agree with you, the seasickness
is not a mental state neither a state of mind: I rather think it's the logical cause of a serial of disturbances on the brain and in the brain. Some people don´t feel anything with 2 meter waves and, anyhow anothers get quickly a seasick. I sail "solo" and sometimes feel it, but the natural way of getting is a mix of rough seas, bad course and bad mainsail and genoa trimming. In my experience the " solo" navigation it annuls the possibility of having a mental state different from the one to be in continuous alert. But, let's pay attention,i am customary to sail in hard conditions, a person who don´t sail habitually in about of 20 minutes would have an horrible sensation of seasickness. Therefore, we should do two kinds of sailors, those who usually sail and anothers. My comment in this post it has to do with them.

To Pericles. Forgive me, i had no time to put figures, only copy and paste, but the key and the feeling of this post you have caught it, friend

Best winds

Antonio,
Did you work out all those MCR numbers or did you get them from anywhere else?
Anyway I'm interested in knowing the source.

Cheers.

Here the effects of rolling and acceleration when pitching and heaving, on crew capability, taken from Marchaj's

don´t agree with you, the seasickness is not a mental state neither a state of mind:
The times I have been in bad waters and where I was probably supposed to become sea sick there wasn't time to think about getting seasick, it was do or die.

Best position for a seasick passenger(s) is aft and have them look that way. Seems to work too, the water look calmer and they leave you alone to get through the mess while they sit and feel sorry for themselves ;)

I agree with Antonio
If we are talking more experienced sailors for a start then motion fatigue is not a state of mind but a function of exposure. Also the best position for anyone seasick is in a prone position in the most comfortable part of the vessel.

Here's an article on predictive methods from the Australian Naval Architect (May 1999).

I also have some studies from the Australian Navy somewhere the upshot for improved habitability was nothing revolutionary but worth re-stating:

Increase Mass (as the most effective form of damping)
Increase waterline length (reduces pitching)
Avoiding flat sections fore and aft
Keep GM low (within other constraints)
Keep accommodations, workspaces etc close to midships or aft thereof.

Excellent paper Mike, congratulations !!! I´ve just read and it's really impressive. Although it's very technical under my point of view for most of the people. Superb explanation of brain´s reaction due to acceleration.

Guillermo, these are not by myself. Look what nice url!!!

http://www.image-ination.com/sailcalc.html and enjoy it...

Best winds

Nice info, Mike your comment 'Avoiding flat sections fore and aft', could you explain pls ?

Ok, doc, so if somone does become seasick, besides moving the person to the best possible location, is there a medication for this or is it something you just have to live through, incurable but you develop some resistance to it... ?

A deeper V gives a smoother riding hull in a seaway and also considerably reduces pounding ( a rapid deceleration).
The experienced acceleration is a function of the following; Presented waveform, Rate of change of horizontal area, Mass moment of inertia and the relative damping coefficient.

... like some people itch from working with glass before they even touch the stuff... uh..that would be me.:rolleyes:

The human factors associated with seasickness have been studied ad nauseum (pardon the pun) and many factors are still not understood or cross-correlated. Things like horizon view...ventilation..cabin temp..proximity to other passengers (the incidence of MSI going up sharply when several pasengers become ill, causing others to be the same around them..thus it spreads quickly amongst otherwise less-affected passengers). The influence of combined vertical and lateral accelerations is also not well-understood..the detailed studies with subjects in motion simulators were restricted to motion in one axis or the other..
...and so on.

The vast majority of studies (and resultant 'comfort level' parameters) use gross motion parameters (RMS or single-amplitude) and do not consider the frequency distribution of the motions..limiting the utility of the results to application only over a very narrow 'band' of vessel type and size..that from which they were derived in the first place..

A case in point: The early prototype wavepiercing cats appeared to be superior to conventional cats of the time in ride quality terms. It was not until the first 'big' passenger ferry wavepiercer was built that it was discovered that the motion periods were almost 'spot on' the frequency where humans are most susceptible to quickly becoming seasick. At the small scale of the prototypes, the frequency of the motions was well above that critical zone. Oops..

Thanks Antonio.
I already knew Carl's calculator, but hadn't visited in a long time. He has improved it a lot! Very nice source of information.

Cheers.

You're wellcome Guillermo. I plan to travel a few days this Christmas, till then...

Happy Christmas to all

I´ll back

From what I read on the subject, prevention is more effective than a cure. Therefore, remedies must be taken before setting sail. Medication can be obtained from pharmacies which help most people by sedating the balancing organs. http://www.seasickness.co.uk/

I haven't had it often and I don't set sail without dosing up correctly, because I want never to feel so bad again. :P

Here is a line from http://en.wikipedia.org/wiki/Sea-sickness

"drinking any substance that is likely to temporarily diminish their senses of sight and touch" Any ideas what that might mean? Alcohol? In which case, 2 lines down, ginger is mentioned and I like Stones or Crabbies Ginger Wine. :D Could this be the miracle cure?

http://captainwiki.com/index.php?title=Seasickness looks at other suggestions.

Pericles

The wife has a 'Home remedy book' she's been putting together for years. Ginger is well known to turn tummies the right way up, seems the ginger cookies are in, ginger wine is out.

Fanie,

Living in South Africa as you do, you're about as far away as it's possible to get from Scotland, so here is Stones website.

http://www.stonesgingerwine.com/welcome.php

The Special Reserve I buy is 17% by volume and is a lovely winter warmer. Add some Scotch and you have the infamous leg opener, known as the Whisky Mac.

Remember I was asking what this could be.

"drinking any substance that is likely to temporarily diminish their senses of sight and touch"

That's not a ginger bickie. :D

Pericles

Hi Pericles, I intend to keep my distance... your weather suck :D

We in SA don't drink that weak stuff. We have stuff here that runs by the name of 'Mampoer'. It's up to 97% volume and opens all kinds of things not just legs :rolleyes: You don't add anything to it, it's nice just as it is.

Couple a sods of these you could cross oceans...

Fanie,

From what I see below, Mampoer means a sailor doesn't care if he's mal de mer. :D :D :D
http://www.iol.co.za/index.php?set_id=1&click_id=139&art_id=vn20060610091514269C206199

http://www.encounter.co.za/article/179.html

http://everything2.com/index.pl?node_id=1792869

Pericles

I've never seen or heard anyone to get Mal-de-mer while steering the boat. Same with motion sickness in a car driving country roads..
So keeping one's eyes on the way ahead gives the same information to brains as ears with the balance and motion..
Other possibility is to exclude visual reference totally and hit the sack..
No studies just some observations..

I've never seen or heard anyone to get Mal-de-mer while steering the boat........
Other possibility is to exclude visual reference totally and hit the sack..
No studies just some observations..

You can have relatively benign sea states where some crew will function well and some will be vomiting but functional. However when the sea gets more excited then motion induced fatigue is more significant which will effect everyone aboard.

On a passage most of us take around 10 hrs after departure in a seaway before the nausea goes away, but nausea and incapacitation can be quite different. You can be purging your stomach and still be close to 100% functional. O the other hand people can appear well enough (not vomiting) but take considerably longer to acheive simple tasks and also suffer a considerable drop in mental and physical capacity. This is more the concern for the experienced mariner crossing oceans in a small boat. We can consider the related mental incapacitiation to be a serious problem particulalrly in heavy weather. You can manage the nausea to some extent but not the incapacity, and people confuse the two.

Hi MikeJohns,

Is sea sickness a temporary condition that goes away ie you get used to the conditions and not get sea sick any more or is it an idividual problem that will happen to the individual every time under the same conditions ?

you will experience the same levels of nausea-discomfort and or incapacity each time you set out or experience heavy weather.

However psychological factors do change over time as you gain confidence in the vessel and the fear factor reduces.

Your brain learns to anticipate the motion and that takes from anything from a few hours to a few days (depending on the individual). This transition period occurs every time you set foot on the vessel after a period off it.

Interestingly, changing vessels or getting back on land can then be equally disorienting often for around the same period.

I´m back.

Hi MikeJohns,

Is sea sickness a temporary condition that goes away ie you get used to the conditions and not get sea sick any more or is it an idividual problem that will happen to the individual every time under the same conditions ?

My Dad who like me was-is in the merchant navy was seasick after every port call. Apparently his reccommended cure was to thread a cube of pork onto a length of string, swallow it, pull it back up with the string and repeat. What this achieved I have no idea.
I first went to sea at about 16yrs old, was seasick the first trip, and never suffered since, be it on my ship (anchor handling tug), or my 28 feet floating caravan with sails

best regards
Nigel

I´m back.
Welcome back, Antonio and...Feliz Año!
have you been sailing?

Hello friend!!! Happy new year!!! and best wishes for this !

Yes i´ve been sailing but not offshore and not in my sailboat. Please Guillermo i´m very interested in your response about my last post ( First 50 & X-50)

Un abrazo

Best winds

Attached here is an interesting paper to this thread's purposes.

Cheers

Hi Guillermo!!!! I´m gonna take a look in a moment. Sure it´ll be fine

Roll acceleration is not an issue if the boat is heeled enough by the wind pressure against the rig and the superstructure. The real differences comes how well a boat can maintain that steady heeling in different circumstances. In this most of the modern sailboats do fail due their wide beam which naturally resist these "upstream" heeling forces too much and instead live with the "downstream" ie waves:mad:

Antonio,

Will you be so kind to confirm the formula
MCR = Disp / (2/3*((7/10 * LWL)+(1/3 *LOA))*Beam4/3 )
as follows:
does "Beam4/3" mean "Beam^4/3" or "Beam*4/3";
meaning respectively, if no mistake, a MCR dimension in ft^2/3 or ft ?

Even if easy, I did not test it through your comprehensive listing (lack of data immediately available) and simply would like to test my own boat's relative position regarding MCR by your return thread.

Thank you in advance.

Fair winds to all.

Patrick

MCR = Disp/(0.65*(B^4/3)*(0.7*Lwl+0.3*Lh))
http://www.tedbrewer.com/yachtdesign.html

Note:
B = Bmax
Lh = Length of hull (in many places named as LOA)
All units imperial.

Cheers.

To Patrick:

Trust Guillermo. He´s a true professional. As far as i know the formula is as follows:

MCR = Disp / (2/3*((7/10 * LWL)+(1/3 *LOA))*Beam4/3 )

Best winds

Thanks Antonio, but the man to trust is Ted Brewer, the father of the MCR, not me.
Cheers.

Antonio, Guillermo,

Thanks a lot to you both and to Ted BREWER moreover.

So, if you agree, the dimension of MCR is d, expressed as [ft^(2/3)] i.e. d as [cubic root of square feet].

My own 35 footer is thus MCR = 21d...
I guess that's not enough to make my family as comfortable as onboard a famous Colin Archer.

Fair winds and compulsory smooth seas, then to expect.

Kindly.

Patrick

Calm down, Patrick, a Transpac 52 only score 16 and in my own case , (i have a Beneteau 473) my sailboat score 26.7. Be a good trimmer avoiding low pressure systems, don´t save your money in navtex,weather-fax, HF radio, global phone and try to anticipe your movements when you were sailing with family. Personally i know people wich have crossed the Atlantic or the Pacific with lower MCR than your boat. The MCR is a data, the real true data are in your brain, be strong.

Good luck

Good evening Antonio,

Thank you for your personal opinion.

My fundamental concern remains about the standardisation of such ratios depending upon units and considering essential ratios do not, like nondimensional Froude number, for instance.

Kindly.

Patrick

I just found this thread, read over all your posts, and skimmed through some of the documents posted as well (will look more thoroughly later). Some random notes:

Modern racing sailboats, due to their light weight and broad beam, are very 'snappy' compared to older, heavier displacement hulls. This is good for speed and acceleration after turning around a mark; it's rough on the sailors. From what I hear, it's a constant challenge to avoid being launched across the cockpit... Good exercise, though! This would explain why a Transpac 52 would only score a 16 (or whatever--can't recall) on the Motion Comfort Index, while even my little Catalina 27 scores about 25.

Catamarans have an odd reputation regarding seasickness--whereas a monohull boat has a relatively predictable (although large) motion in a sea, a multihull has each hull riding on different parts of the waves, and therefore has a quite unpredictable and rather disconcerting motion. I've read of several instances where experienced monohull sailors found they suffered more seasickness on a Cat, even though there was little real motion. Strange...

Finally, my wife and I visited a boat owned by two licensed captains, who told us of an herbal remedy called Motion-Ease, sold by West Marine. They insist than anyone who comes on board dab a drop or two behind each ear, and they swear that in the three years they've sailed their 42' Endeavour, they've never had a single case of seasickness aboard.

Sorry this is all hearsay--but take it for what it's worth.:rolleyes:

Modern racing sailboats, due to their light weight and broad beam, are very 'snappy' compared to older, heavier displacement hulls. This is good for speed and acceleration after turning around a mark; it's rough on the sailors. From what I hear, it's a constant challenge to avoid being launched across the cockpit... Good exercise, though! This would explain why a Transpac 52 would only score a 16 (or whatever--can't recall) on the Motion Comfort Index, while even my little Catalina 27 scores about 25.

Sorry this is all hearsay--but take it for what it's worth.:rolleyes:

How do you spell rubbish?

Most "modern" racing sailboats (discounting the Open boats that are beamy due to a rule) are very moderate in beam compared to boats 20-30 years ago. You must be reading the same tired crap that's been written since the 1970s.

I have sailed and raced many modern (and older) boats and have never found any "challenge to avoid being launched across the cockpit". Just what would cause this, short of the mast miraculously disappearing?

As a one time Catalina 27 National Champion I have no small experience sailing those boats, and I can tell you that modern racing boats are far more motion friendly than an old Cat 27, especially in a quartering sea. The excess displacement and horrible rudder design of the Cat 27 makes it "good excercise" compared to a modern raceboat.


This is yet another thread about the Motion Comfort Ratio, a rubbish calculation that means nothing. The fact that people use it to make any comment on a design should make Brewer hang his head in shame.

Good morning,

An overseas genuine and quite ancient recipe aged two centuries must be known from our community of the "third kind", according to Aristote's classification of "those who sail", using following thread http://www.passocean.com/dddeuxsieclesdhistoire/deuxsieclesdhistoire.html

It appears a beverage to sip once before letting go !

Thanks to all.

Patrick

How do you spell rubbish?
r-u-b-b-i-s-h;)

Most "modern" racing sailboats (discounting the Open boats that are beamy due to a rule) are very moderate in beam compared to boats 20-30 years ago.
Aren't the open boats modern or what? And what comes to beam it's not only the max beam instead of overall beam
You must be reading the same tired crap that's been written since the 1970s.
Why to torture yourself, just skip the crap and look elsewhere:rolleyes:
I have sailed and raced many modern (and older) boats and have never found any "challenge to avoid being launched across the cockpit". Just what would cause this, short of the mast miraculously disappearing?
If I recall right there have been some dismastings with modern racers
This is yet another thread about the Motion Comfort Ratio, a rubbish calculation that means nothing. The fact that people use it to make any comment on a design should make Brewer hang his head in shame
a hearsay:P !

Teddy,

Dura lex, sed lex ! Nothing but the law ?

Isn't this an open discussion in the vicinity of the initial thread: "The roll acceleration: What's the best for crossing oceans" ?

I do have a deep respect for that ratios myself especially to share and improve them in our field, well known for its "rule of thumb" and intuition that anyway made so efficient and beautiful famous ocean crossing yachts.

Pleasure.

Patrick

How do you spell rubbish?
Obviously I use a different spelling than you; we seem to disagree on a lot!

Most "modern" racing sailboats (discounting the Open boats that are beamy due to a rule) are very moderate in beam compared to boats 20-30 years ago. You must be reading the same tired crap that's been written since the 1970s.
What I'm reading are magazines like Sail, discussions in the Sailing Anarchy website, postings on the C-27/C-270 message list, and books like Desirable and Undesirable Characteristics of Offshore Yachts as published by the ORC. What I read are descriptions of what it's like to sail on Open boats, Transpac boats (like the Transpac 52 that was brought up in earlier posts on this forum) and what I see are pictures of boats with wide, fairly flat beams, broad aft and fine forward. And these boats are recent--not ones necessarily from 20-30 years ago.

I have sailed and raced many modern (and older) boats and have never found any "challenge to avoid being launched across the cockpit". Just what would cause this, short of the mast miraculously disappearing?
Well, as someone else noted, there do seem to be a lot of dismasted ocean racers lately, and some that have lost keels as well. But what I'm thinking is that a broad light hull with very high initial stability, coupled with a heavy lead bulb held very deep by a high aspect ratio keel and providing a quite-lengthy moment arm to a weight that's a high percentage of the overall displacement would result in a hull that would want to snap back upright quite quickly compared to an older bluewater boat. I would also suggest (and in all of this I'm just echoing what more experienced boat designers and sailors have been writing) that carbon fiber rigs and high-tech sails have a much lower inertia as well, which also allows the boat to 'snap' upright, or quickly heel in a gust or beam sea, or heave in the waves.

As a one time Catalina 27 National Champion I have no small experience sailing those boats, and I can tell you that modern racing boats are far more motion friendly than an old Cat 27, especially in a quartering sea. The excess displacement and horrible rudder design of the Cat 27 makes it "good excercise" compared to a modern raceboat. Are you talking about a modern 27-foot raceboat? For example? With all due respect to your championship, I only brought up the C-27 as a contrast to the Transpac 52--a boat twice her length has an MCI that's 2/3 of mine.


This is yet another thread about the Motion Comfort Ratio, a rubbish calculation that means nothing. The fact that people use it to make any comment on a design should make Brewer hang his head in shame.
This is a thread about roll rate and seasickness. The Motion Comfort Index isn't perfect, but it's one of the tools that's been used to discuss differences between boats. It's not a perfect tool but this isn't a black and white world; whatever isn't perfect isn't automatically rubbish. Perhaps your world, however, IS black and white?

This is a thread about roll rate and seasickness. The Motion Comfort Index isn't perfect, but it's one of the tools that's been used to discuss differences between boats. It's not a perfect tool but this isn't a black and white world; whatever isn't perfect isn't automatically rubbish. Perhaps your world, however, IS black and white?

No, my world is a world of facts, not repeating silly comments over and over for years, as if that makes them true.

Originally Posted by Paul B
How do you spell rubbish?

Obviously I use a different spelling than you; we seem to disagree on a lot!

Most "modern" racing sailboats (discounting the Open boats that are beamy due to a rule) are very moderate in beam compared to boats 20-30 years ago. You must be reading the same tired crap that's been written since the 1970s.


What I'm reading are magazines like Sail, discussions in the Sailing Anarchy website, postings on the C-27/C-270 message list,

(You do realize one needs no expertise to be published in sailig periodiacals or on websites and message boards)

and books like Desirable and Undesirable Characteristics of Offshore Yachts as published by the ORC. What I read are descriptions of what it's like to sail on Open boats, Transpac boats (like the Transpac 52 that was brought up in earlier posts on this forum) and what I see are pictures of boats with wide, fairly flat beams, broad aft and fine forward. And these boats are recent--not ones necessarily from 20-30 years ago.

Let's look at the TP 52, since you want to talk about it. It is fairly representative of a modern raceboat. Canting keelers and AC boats are narrower, Open boats (a very small subset of the racing boat set) are wider.

The TP52 has a B/L of 0.28. The B/DWL is the same.
The STP 65 (big sister to the TP 52) has a B/L of 0.24.
The Catalina 27 has a B/L of 0.33. The B/DWL is 0.38.
Finisterre had a B/L of 0.29. The B/DWL was 0.41.

So let's talk about the "evil, beamy" boats, shall we?

I have sailed and raced many modern (and older) boats and have never found any "challenge to avoid being launched across the cockpit". Just what would cause this, short of the mast miraculously disappearing?

Well, as someone else noted, there do seem to be a lot of dismasted ocean racers lately, and some that have lost keels as well.

And this has exactly WHAT to do with the MCR? It was a silly statement for the other person to make, and even sillier for you to repeat.

But what I'm thinking is that a broad light hull with very high initial stability, coupled with a heavy lead bulb held very deep by a high aspect ratio keel and providing a quite-lengthy moment arm to a weight that's a high percentage of the overall displacement

None of this is part of the MCR calculation

would result in a hull that would want to snap back upright quite quickly compared to an older bluewater boat.

And what would cause it to "snap back"? There are forces that cause the heeling moment that the righting moment is working against. Are you trying to say that it suddenly, completely disappears? Not in any of the thousands of miles I've ever sailed.

I would also suggest (and in all of this I'm just echoing what more experienced boat designers and sailors have been writing) that carbon fiber rigs and high-tech sails have a much lower inertia as well, which also allows the boat to 'snap' upright, or quickly heel in a gust or beam sea, or heave in the waves.

How on earth do you think lighter rigs make a boat "quickly heel" or heave more? More BS people like you love to lap up and regurgitate.

As a one time Catalina 27 National Champion I have no small experience sailing those boats, and I can tell you that modern racing boats are far more motion friendly than an old Cat 27, especially in a quartering sea. The excess displacement and horrible rudder design of the Cat 27 makes it "good excercise" compared to a modern raceboat.

Are you talking about a modern 27-foot raceboat? For example? With all due respect to your championship, I only brought up the C-27 as a contrast to the Transpac 52--a boat twice her length has an MCI that's 2/3 of mine.


Yes, I own a modern 27 foot raceboat. It is very light (D/L <90), but narrow (B/L 0.27). It never "snaps back" with any sort amplitude or frequency that would throw anyone across the cockpit. Belive me, the TP 52 is a boat you would much rather be on in bad weather compared to your Cat 27, regardless of the meaningless ratio you so love to embrace.

No, my world is a world of facts, not repeating silly comments over and over for years, as if that makes them true.


Paul could you please list the comments which in your opinion you find so 'Silly' along with some of the immutable facts you possess so we can all learn.

There seems to be a mindset amongst some people that where the science of Naval-architecture conflicts with their belief then the science is somehow mis-informed. These tend to be the very people with no foundation in NA who are so quick to discount studies and research that challenges their ‘facts’.

For example:
You need to consider the role that well placed mass plays in damping all the motions of a vessel. Also consider all conditions the vessel will encounter and how it will respond in those conditions. Don’t just pick the ideal conditions for that particular hull-form and then extrapolate that across the board.

Contemporary racing designs can experience some very uncomfortable and jerky motions, you just have not considered when this is likely to occur.


How on earth do you think lighter rigs make a boat "quickly heel"? …..More BS people like you love to lap up and regurgitate.

Roll inertia certainly changes the rate at which the vessel can vary in heel angle (mass times the square of the distance from the roll axis ). Consequently even light rigs have a very significant effect along with ballast. Motion without the rig in ballasted keelboats becomes violent in a boisterous seaway for this very reason. The loss of this damping is also responsible for a dismasted vessel being rolled repeatedly despite the lowered COG (improved static stability) after losing the mast.

Totally unfair and of little use to compare a 52' with a 27', whatever the ratios.
MCR gives a reasonable clue on a yacht's heaving behaviour. The philosophy behind this ratio has been strongly supported by exhaustive studies other than Ted Brewer's, and I wouldn't dare to say it's rubbish. Sustaining that only shows lack of knowledge (and prudence) in my opinion. MCR is only intended for displacement speeds, not for planning ones where hydrodynamic forces are in command.
On the other hand what is important for an all-around-go-anywhere family cruiser doesn't necessarily has to apply to a racer-cruiser mainly intended for coastal waters racing for relatively short periods of time with well trained crews.
What is clear and thoroughly proven is that a beamier and lighter boat will show bigger vertical accelerations than a narrower and heavier one. Vertical accelerations may be more seasickness inducing than rolling ones in a sailboat, as these last are dampened by the wind force on sails, except in the weaker winds.
What would be very nice is to not begin again with personal disqualifications when discussing these matters. We have had enough of those already.
Cheers.

Paul B, I'm starting to understand that you're not really interested in straightforward discussion of ideas. But I'll provide this information just to see if you are:

(You do realize one needs no expertise to be published in sailig periodiacals or on websites and message boards)
And so? You appear to imply that those who are published do not have expertise. Surely that's not what you truly believe!

And what would cause it to "snap back"? There are forces that cause the heeling moment that the righting moment is working against. Are you trying to say that it suddenly, completely disappears?
Lack of roll moment inertia, and high ballast/displacement ratio. As I said before, the boats I'm discussing have very high initial stability. This makes them return or recover very quickly relative to an older, more traditional design--and in rough water they're going to have a very different motion.

The TP52 has a B/L of 0.28. The B/DWL is the same.
The STP 65 (big sister to the TP 52) has a B/L of 0.24.
The Catalina 27 has a B/L of 0.33. The B/DWL is 0.38.
Finisterre had a B/L of 0.29. The B/DWL was 0.41.
Obviously, ratios of beam to length don't tell the whole story. You're too focused on just one element of design. Look at Finisterre vs. the TP52--similar B/L, but vastly different B/DWL--because the Finisterre had magnificent overhangs, giving her a long of pitch inertia and plenty of reserve buoyancy (unlike the TP52, which has a plumb bow, I would assume, from the fact that her B/DWL is the same as her B/L). She was also the leader of the movement toward beamy, roomy centerboarders. She displaced 11 tons on a waterline of only 27 1/2 feet. What's the displacement of the TP52?

How on earth do you think lighter rigs make a boat "quickly heel" or heave more? More BS people like you love to lap up and regurgitate.
Okay, here's some information from a chapter in Desirable and Undesirable Characteristics of Offshore Yachts, 1987 Edition. This chapter was co-authored by Karl Kirkman, a naval architect and marine engineer with extensive work in 12-Meter and ocean-racing yacht development, and by Richard McCurdy, chairman of the USYRU's Safety at Sea Committee and a former CCA commodore. On page 61, they write about tank tests that found behavior of boats capsized by wave action was controlled by dynamic principles rather than static flotation, and that when properly scaled masts were mounted on tank models, the models wouldn't capsize anymore when struck by waves that readily capsized the mastless models. This seemed counter-intuitive, since you'd think a mastless hull has to float more staunchly upright...
When they thought about the roll moment of inertia, they noted that the heavier parts of the boat are located close to the roll axis. But the rig, although lighter, was much farther away, and constitutes "over half of the total roll inertia, in boats both big and small."

So what I'm saying again (I mean, regurgitating) is that a lighter rig makes a boat have a much lower roll inertia, and therefore it's going to be much more reactive in a sea.

Does this make sense to you yet or not?

Paul could you please list the comments which in your opinion you find so 'Silly' along with some of the immutable facts you possess so we can all learn.

I've watched your discussions in the past and plainly see you don't learn very well. Keep telling everyone how unsafe things are, maybe you'll sell more of your product. Yep, if it isn't a steel hulled, long keeled boat designed by the greatest ENGINEER in all of sailing, then you are taking your life in your hands.

You may or may not realize it, but there are some pretty damn good engineers designing boats of the type you don't like.

There seems to be a mindset amongst some people that where the science of Naval-architecture conflicts with their belief then the science is somehow mis-informed. These tend to be the very people with no foundation in NA who are so quick to discount studies and research that challenges their ‘facts’.

If you think the MCR is SCIENCE then there is little hope for you.

For example:
You need to consider the role that well placed mass plays in damping all the motions of a vessel. Also consider all conditions the vessel will encounter and how it will respond in those conditions. Don’t just pick the ideal conditions for that particular hull-form and then extrapolate that across the board.

Contemporary racing designs can experience some very uncomfortable and jerky motions, you just have not considered when this is likely to occur.

Please enlighten us, when is it likely to find modern designs "snapping" to and fro, pitching helpless sailors across the cockpit?




Roll inertia certainly changes the rate at which the vessel can vary in heel angle (mass times the square of the distance from the roll axis ). Consequently even light rigs have a very significant effect along with ballast. Motion without the rig in ballasted keelboats becomes violent in a boisterous seaway for this very reason. The loss of this damping is also responsible for a dismasted vessel being rolled repeatedly despite the lowered COG (improved static stability) after losing the mast.

I've been on mastless boats, and they do have scary accelerations. I've also sailed on identical class boats with both tin and carbon rigs. You couldn't notice any difference in roll or pitch. I know there was a change, but it is not something you feel. Ditto changing from Dacron to Kevlar sails.

When out puttering about without sails up boats can roll about a bit. Once you put the main up things quiet down. The drag of the sail is a great dampening device, eh? Maybe that's why powerboaters use steadying sails? If a little steadying sail on a big trawler works, why don't you think the big main and headsails on sailboats act in the same way?

What is clear and thoroughly proven is that a beamier and lighter boat will show bigger vertical accelerations than a narrower and heavier one.


Let's anchor two boats side by side in an area with the waves coming from the bow. One boat is narrow and heavy, the other light and beamy.

As the waves come toward the boats the bows lift and the boats eventually crest and drop into the next trough.

Which of the boats has a greater vertical acceleration?

Paul B, I'm starting to understand that you're not really interested in straightforward discussion of ideas. But I'll provide this information just to see if you are:

(You do realize one needs no expertise to be published in sailig periodiacals or on websites and message boards)
And so? You appear to imply that those who are published do not have expertise. Surely that's not what you truly believe!

There are many people who are published who don't have any idea what they are talking about. I know this for a FACT.

And what would cause it to "snap back"? There are forces that cause the heeling moment that the righting moment is working against. Are you trying to say that it suddenly, completely disappears?
Lack of roll moment inertia, and high ballast/displacement ratio. As I said before, the boats I'm discussing have very high initial stability. This makes them return or recover very quickly relative to an older, more traditional design--and in rough water they're going to have a very different motion.

Again, the MCR does not take any of this into consideration. It does not take stability into account at all.

The TP52 has a B/L of 0.28. The B/DWL is the same.
The STP 65 (big sister to the TP 52) has a B/L of 0.24.
The Catalina 27 has a B/L of 0.33. The B/DWL is 0.38.
Finisterre had a B/L of 0.29. The B/DWL was 0.41.
Obviously, ratios of beam to length don't tell the whole story. You're too focused on just one element of design. Look at Finisterre vs. the TP52--similar B/L, but vastly different B/DWL--because the Finisterre had magnificent overhangs, giving her a long of pitch inertia and plenty of reserve buoyancy (unlike the TP52, which has a plumb bow, I would assume, from the fact that her B/DWL is the same as her B/L). She was also the leader of the movement toward beamy, roomy centerboarders. She displaced 11 tons on a waterline of only 27 1/2 feet. What's the displacement of the TP52?

I am not focused on any element. I am focused on actual performance. You're the one who made a claim that a TP52 was some overly beamy design with a crap MCR compared to your Cat 27. I was simply educating you.

Your choice of words, "magnificent overhangs" tells me a lot about your point of view. I've sailed on TP52s. Have you? They may not have the kind of "reserve bouyancy" you like to see, but they don't go down the mine either. I can't say that for the Cat 27. See what happens when you get in large waves with that.

How on earth do you think lighter rigs make a boat "quickly heel" or heave more? More BS people like you love to lap up and regurgitate.
Okay, here's some information from a chapter in Desirable and Undesirable Characteristics of Offshore Yachts, 1987 Edition. This chapter was co-authored by Karl Kirkman, a naval architect and marine engineer with extensive work in 12-Meter and ocean-racing yacht development, and by Richard McCurdy, chairman of the USYRU's Safety at Sea Committee and a former CCA commodore. On page 61, they write about tank tests that found behavior of boats capsized by wave action was controlled by dynamic principles rather than static flotation, and that when properly scaled masts were mounted on tank models, the models wouldn't capsize anymore when struck by waves that readily capsized the mastless models. This seemed counter-intuitive, since you'd think a mastless hull has to float more staunchly upright...
When they thought about the roll moment of inertia, they noted that the heavier parts of the boat are located close to the roll axis. But the rig, although lighter, was much farther away, and constitutes "over half of the total roll inertia, in boats both big and small."

So what I'm saying again (I mean, regurgitating) is that a lighter rig makes a boat have a much lower roll inertia, and therefore it's going to be much more reactive in a sea.

Does this make sense to you yet or not?

See my comments to Eng. Johns. Tell me why one might sail a J120 with a carbon rig and another with an aluminum ring and not notice any difference in pitch or roll.

I'm still waiting to hear some real info about this "snapping" motion of modern boats that pitches poor sailors headlong across the cockpit.

Let's anchor two boats side by side in an area with the waves coming from the bow. One boat is narrow and heavy, the other light and beamy.

As the waves come toward the boats the bows lift and the boats eventually crest and drop into the next trough.

Which of the boats has a greater vertical acceleration?

The light and beamy one--less inertia. It's going to lift faster and drop faster. This isn't about gravity--it's a dynamic analysis. That's the whole point.

Again, the MCR does not take any of this into consideration. It does not take stability into account at all.

I am not focused on any element. I am focused on actual performance. You're the one who made a claim that a TP52 was some overly beamy design with a crap MCR compared to your Cat 27. I was simply educating you.


I never typified the TP52 as some overly beamy design. I mentioned several factors, lightness among them.

I don't understand how you miss the stability element of Ted Brewer's MCR, which he admits was a tongue-in-cheek idea in the first place but it turns out to a be a fair way to judge boats of similar design.

In Ted's own words: "Given a wave of X height, the speed of the upward motion depends on the displacement of the yacht and the amount of waterline area that is acted upon. Greater displacement, or lesser WL area, gives a slower motion and more comfort for any given sea state.

Beam does enter into it as as wider beam increases stability, increases WL area, and generates a faster reaction. The formula takes into account the displacement, the WL area, and adds a beam factor. The intention is to provide a means to compare the motion comfort of vessels of similar type and size, not to compare that of a Lightning class sloop with that of a husky 50 foot ketch"

The MCR accounts for displacement, beam, and length, but if you examine the formula, it is also accounting for the ratio between LOA and LWL, which contributes to pitch inertia.

I never typified the TP52 as some overly beamy design. I mentioned several factors, lightness among them.


Here, I am sure you mention broad Beam:


Modern racing sailboats, due to their light weight and broad beam, are very 'snappy' compared to older, heavier displacement hulls. .. This would explain why a Transpac 52 would only score a 16 (or whatever--can't recall) on the Motion Comfort Index.


I don't understand how you miss the stability element of Ted Brewer's MCR, .

Because it is not there.

which he admits was a tongue-in-cheek idea in the first place but it turns out to a be a fair way to judge boats of similar design..

Finally someone reads what Brewer said himself. It was a joke to begin with (and remains a joke). A fair way to to judge boats, not many professionals would think so.

In Ted's own words: "Given a wave of X height, the speed of the upward motion depends on the displacement of the yacht and the amount of waterline area that is acted upon. Greater displacement, or lesser WL area, gives a slower motion and more comfort for any given sea state.

Beam does enter into it as as wider beam increases stability,.

Are you sure about that? The MCR does not specify BWL.

increases WL area, and generates a faster reaction. The formula takes into account the displacement, the WL area, and adds a beam factor. The intention is to provide a means to compare the motion comfort of vessels of similar type and size, not to compare that of a Lightning class sloop with that of a husky 50 foot ketch".

However, the anti-moderate mob always likes to pull this calculation out as if it is some sort of magic formula, simply because it shows their boats in a better light.

The MCR accounts for displacement, beam, and length, but if you examine the formula, it is also accounting for the ratio between LOA and LWL, which contributes to pitch inertia.

I think you are reading the wrong thing into the equation. The use of 70% DWL and 30% LOA is a crude way to approximate the actual sailing length of the boat. Similar calcs have been used in many rating formulas over the years. It has nothing to do with calculating any pitch inertia.


OK, compare two boats. Both have LOA 50 feet. Both have LWL 42 feet. Both have a beam of 12 feet and a DSPL of 25,000 lbs.

One has a shallow (5 feet draft), full keel with a lot of internal ballast. It has a normal masthead cutter rig of 60 feet "I".

The other boat has an America's Cup Class style keel, 12 foot deep thin steel fin and 15,000 pounds of bulb at the bottom. Oh, and there is no mast.

These two boats HAVE THE SAME MCR.

R-u-b-b-i-s-h.

The light and beamy one--less inertia. It's going to lift faster and drop faster. This isn't about gravity--it's a dynamic analysis. That's the whole point.

Hmm,

The two boats are anchored next to one another. The wave it the same height for both and passes under both at the same velocity.

They both rise to the top of the wave together and drop to the trough together.

The only way for the lighter boat to rise faster is if it is moving forward faster than the heavy boat. But they are both going the same speed (the speed of the wave passing beneath), so how can one rise faster than the other?

Magic?

Here, I am sure you mention broad Beam:
Yes, I mentioned broad beam. I also mentioned light weight. You somehow keep missing that.



Originally Posted by drshaddock
I don't understand how you miss the stability element of Ted Brewer's MCR, .

Because it is not there.
The only reason I can imagine why you don't see stability as part of the equation is that you still don't grasp some of the factors that contribute to stability--both dynamic and static.


Originally Posted by drshaddock
In Ted's own words: "Given a wave of X height, the speed of the upward motion depends on the displacement of the yacht and the amount of waterline area that is acted upon. Greater displacement, or lesser WL area, gives a slower motion and more comfort for any given sea state.

Beam does enter into it as as wider beam increases stability,.

Are you sure about that? The MCR does not specify BWL.
Those are Ted's words, not mine. You can ask him if he's sure. But don't bother commenting that the MCR does not specify BWL--you're right. But there was no mention of BWL. The MCR just factors in Beam.

Originally Posted by drshaddock
increases WL area, and generates a faster reaction. The formula takes into account the displacement, the WL area, and adds a beam factor. The intention is to provide a means to compare the motion comfort of vessels of similar type and size, not to compare that of a Lightning class sloop with that of a husky 50 foot ketch".
However, the anti-moderate mob always likes to pull this calculation out as if it is some sort of magic formula, simply because it shows their boats in a better light.
Hmm... never thought of myself as being part of a mob, and I'm not sure what anti-moderate is. But I don't pull out MCR because it shows my boat in a better light; heck, the C-27 doesn't really come out all that high!

The other boat has an America's Cup Class style keel, 12 foot deep thin steel fin and 15,000 pounds of bulb at the bottom. Oh, and there is no mast.
She'll sure be slow. Or does she use a sailkite?

Hmm,

The two boats are anchored next to one another. The wave it the same height for both and passes under both at the same velocity.

They both rise to the top of the wave together and drop to the trough together.

The only way for the lighter boat to rise faster is if it is moving forward faster than the heavy boat. But they are both going the same speed (the speed of the wave passing beneath), so how can one rise faster than the other?

Magic?
No--you're completely missing the inertia part of the concept. You [B]have[B] taken a physics class somewhere along the way, have you not? Newton figured it out centuries ago--his Law of Momentum Conservation.

Hmm,

The two boats are anchored next to one another. The wave it the same height for both and passes under both at the same velocity.

They both rise to the top of the wave together and drop to the trough together.

The only way for the lighter boat to rise faster is if it is moving forward faster than the heavy boat. But they are both going the same speed (the speed of the wave passing beneath), so how can one rise faster than the other?

Magic?
I think you should read some basic books before coming into this kind of discussions. May I suggest Marchaj's venerable "Seaworthiness..."? I'm afraid you are bringing to light a certain lack of understanding of some elementary physical phenomena.
Cheers.

Pleasure.
Sorry Patric, I was only commenting Paul B(S), just forget the "quote"
It sure looks like he irriteted others too..
Maybe better to ignore or something..

Salu! Teddy

After all there's something we all agree?:D
When out puttering about without sails up boats can roll about a bit. Once you put the main up things quiet down. The drag of the sail is a great dampening device, eh? Maybe that's why powerboaters use steadying sails? If a little steadying sail on a big trawler works, why don't you think the big main and headsails on sailboats act in the same way?

Let's anchor two boats side by side ………...Which of the boats has a greater vertical acceleration?

The acceleration is variable with time as the wave passes since the vessels do not leave the water it is a complex solution. Firstly you need to define the wave shape, period, and amplitude then you need to know the rate of change of the volume of the vessel as it intersects that wave (which alters along with the vessels response), then you need to calculate acceleration from the resulting change in centre of buoyancy which requires a knowledge of the mass distribution (Inertia), a hydrodynamic damping coefficient (zeta) then you end up with a characteristic higher order differential equation which is not trivial in it's solution, there will also need to be some assumptions refined through observation.


I've watched your discussions in the past and plainly see you don't learn very well. ………..

You want me to learn your ‘Truth’ without any discourse? It seems to me that the boot is on the other foot, but I would rather discuss naval architecture than discuss your personal slurs. Perhaps in the future you could actually contribute something rather than ‘watching’.

Yep, if it isn't a steel hulled, long keeled boat ……………..then you are taking your life in your hands.

Why this imagined duality? If you have ever designed any offshore boats surely you would be aware of the tradeoffs and compromises in vessel design?

What don’t you agree with that we have so far been discussed? Relevant to your interests would be:

Inversion times after capsize related to low AVS
Keel strength issues
Design life
Collision and grounding damage resistance
The likelihood of certain types of vessels to be endangered in heavy weather.

When debating these issues you as ‘PaulB’ have not contributed anything significant at all except for the occasional jibe, and pretending a superior position.
You can always open a thread and discuss your views and I will be happy to contribute.


You may or may not realize it, but there are some pretty damn good engineers designing boats of the type you don't like.

Who are they and what don’t I like about their designs?


In Australia there are chiefly two prominent professional engineers who design lightweight performance vessels under their own banner. Both of these engineers have recently been voicing concerns over lightweight design trends. One of their frustrations is that they are bound to produce designs for heavier (stronger) vessels than designers without proper engineering knowledge.


Please enlighten us, when is it likely to find modern designs "snapping" to and fro, pitching helpless sailors across the cockpit?

Flinging satellites into orbit? This is your interpretation but it is not what I asked you to consider .

The drag of the sail is a great dampening device………….

It’s called damping not dampening (to make wet).
Sails can also excite rolling. This depends on the course sailed relative to the conditions (wind and sea) levels of parametric coupling etc

Gentlemen,

There are those whose opinions, up with which, I will not put!

(Never end a sentence with a preposition, Sir Winston Churchill).

In such situations I go to the recalcitrant offenders' profiles and add them to my ignore list. Thus, I am informed of a "ignored" contribution to a thread, but my sense of wellbeing remains intact, as my eyes are spared the task of informing my brain about the contents of the post.

There are some good and some not so good consequences to such an action. :P :P :P :P

Hello, hello, is anyone out there. I am not getting posts nor am I getting replies to mine. Why am I so unloved, why, why? It's not my fault nobody wants to communicate with me . I did nothing wrong, d'you hear! Please!:D

Best wishes ,

Pericles

You want me to learn your ‘Truth’ without any discourse?
..
When debating these issues you as ‘PaulB’ have not contributed anything significant at all except for the occasional jibe, and pretending a superior position.
..
It’s called damping not dampening (to make wet).
Sails can also excite rolling. This depends on the course sailed relative to the conditions (wind and sea) levels of parametric coupling etc


Sorry I haven’t replied to you and your boy Willie immediately. I was off this weekend racing on a boat that is similar in size and weight to a TP52, but beamier (B/L = 0.29). No one was in danger of being thrown across the cockpit at any time. No one experienced any snappy vertical acceleration that made anyone sick. In fact, one person who came along was doing his first race, and first ride on a performance boat after years of sailing. At the end his grin was incredibly huge, and he could not believe he had sailed for so long without seeing what it is like to sail on that type of boat.


Your ilk continue to make misleading statements simply because you can’t compete in the marketplace without dodgy scare tactics. It reminds me of the designer (MSc NA) back in the late 70s and early 80s who wrote an editorial in the publication of the Royal Ocean Racing Club stating only people with NA behind their name should be allowed to design boats. He simply could not compete on the course or in the order books and was frustrated. I believe his statement included something to the effect (paraphrasing here): “I am tired of losing races and commissions to glorified boat nannies.”


People believe and repeat what they read, and when writing includes exaggerated, inflammatory language like “snap back” it is even more powerful. Of course that is often the intent of the writer. Fear makes it easier to prey on the uneducated. When people write, read, and regurgitate comments about the dangers of “beamy modern boats” they certainly are not actually looking into the facts. But that sort of lemming mindset plays right into your purpose.


A consequence of the continued publishing of exaggerated BS is unwarranted legislation in the US, EU, and other places. It is a growing trend in the EU across many industries, and a cottage industry has sprung up for people who make their living by limiting our choices and “making us safer.” I am sure you have heard of the most terrifying phrase in the English language, “We are from the government and we are here to help you.” More government intrusion into sailor’s lives is not necessarily better.


You talk about people not having reasonable discussions with you. It is no wonder, just check your recent record:


You have posted a ridiculous statement about heavier boats being faster than light racing boats, which you could not substantiate, and when pressed you used an example that showed you either did not understand the difference between elapsed time and corrected time, or you were attempting