I'll show you mine, if you'll show me yours...

[Twister_Ken]

I\'ll show you mine, if you\'ll show me yours...

...comfort factor, that is.

There a page at <A target="_blank" HREF=http://www.image-ination.com/sailcalc.html>http://www.image-ination.com/sailcalc.html</A> that calcualtes various values for a boat, including a Capsize Ratio and a Motion Comfort factor.

For a Twister, these come out as:

Capsize ratio 1.55 (less than 2 is good)
Motion Comfort 37.78 (range from 5 to 60 - higher is better)

How do other buggaz luggers compare?

 

[tillergirl]

Re: I\'ll show you mine, if you\'ll show me yours...

Very good - where do you find these? Motion 47.08, capsize 1.47. Tillergirl is a one off design from 1964, shallow draft, bow like a vertue (only bigger) and a bum like a Bawley (that's what the yard used to build). She is cumfy in a seaway but I've never been too sure about the capsize bit, she is initially a little bit tender which makes the leedeck a tad wet in a largish beam sea. SWMBO once said in the middle of the channel "You can get that bit of the boat out of the water - NOW"

 

[Badger]

Re: I\'ll show you mine, if you\'ll show me yours...

What was your hull speed ?

 

[Chris_Robb]

Re: I\'ll show you mine, if you\'ll show me yours...

Victory 40/Trintella IV
Capsize Ratio: 1.49
Motion Comfort 49.94

I'll see you go tits up first!!

 

[tillergirl]

Re: I\'ll show you mine, if you\'ll show me yours...

6.63 for me

 

[Chris_Robb]

Re: I\'ll show you mine, if you\'ll show me yours...

7.5 for the Victory

 

[AndrewB]

Hey, mine\'s different from yours ..

I've been using John Holtrop's site <A target="_blank" HREF=http://www.johnsboatstuff.com/Articles/best.htm>http://www.johnsboatstuff.com/Articles/best.htm</A>, which also gives stats for about 1,100 boats - but different from those on Carl Adler's site. The figures for the same yachts are a little different too. This site includes my yacht but not yours:

Capsize ratio - 1.69
Comfort factor - 32.6

Holtrop reckons 6 other design parameters are also relevant to chosing 'best' cruising design, these include

Displacement / LWL ratio,
Sail Area / Displacement ratio,
Velocity Ratio,
Length/Beam ratio,
Roll Period,
Roll Acceleration.

(See site for definitions). Some of these are also given by Carl Adler's calculator. Incidentally the "best" well-known yacht across all eight criteria is the Hallberg Rassy 42. The HR42 has figures given by the two sites respectively:

Capsize Ratio: JH - 1.65 CA - 1.72
Comfort Factor: JH - 39.0 CA - 34.1

Oh well, yachting never was an exact science.

 

[bedouin]

Re: I\'ll show you mine, if you\'ll show me yours...

Ours aren't that different.

We get a Cap Size ratio of 1.66, and motion comfort of 34

However I'm surprised that ballast ratio doesn't enter into the equations

 

[ianwright]

Re: I\'ll show you mine, if you\'ll show me yours...

1.31 and 54.1
IanW

<hr width=100% size=1>Vertue 203, Patience

 

[Ohdrat]

Re:How come

a CO 26 has a motion comfort of only 23.94? (The capsize ratio looks a bit more realistic.. at 1.77).. but I would have thought that a CO26 would have had a higher motion comfort ratio??

<hr width=100% size=1>

 

[Fergie]

Re: I\'ll show you mine, if you\'ll show me yours...

Ken
I have been sailing a twister for the last 7 years can, you remember what your hull speed was. VIVEZA out of the elephant yard Hamble

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[Twister_Ken]

Twister\'s hull speed

comes out at 6.21 - which considering we did 6.6 nm in a hour on a channel crossing last year sound a little dodgy

<hr width=100% size=1>

 

[qsiv]

Re: I\'ll show you mine, if you\'ll show me yours...

Fascinating ..

Current boat
Capsize Ratio 1.6
Comfort 51

That boats on the market cos SWMBO has 'gone off' sailing (and broken her back), so I'm off for something just a touch racier which will have figures of ..

CR 2.09
Comfort 13.6
SA/D 39.3

and lies at the opposite end of the speed sprectrum .... SWMBO wont be sailing, so I'm off racing!

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[jamesjermain]

Cruiser racer

To give figures for a typical, more modern, cruiser racer, Scanmar 33 (1984) Capsize 1.99 comfort 22.6. Seems about right to me.

<hr width=100% size=1>JJ

 

[dickh]

Re: Cruiser racer

For a Jaguar 27
Capsize Ratio = 2.01
Motion Comfort = 20.01

<hr width=100% size=1>dickh
I'd rather be sailing... /forums/images/icons/smile.gif

 

[davel]

Re: Cruiser racer

X 332
2.03 and 20.53

<hr width=100% size=1>Dave L.

 

[qsiv]

Re: Cruiser racer

I can believe that - my figures (current boat) are for a Trintella 51A, an big and comfy certainly fits. The New boat figures are for a canting keel sportsboat, which I would expect to be neither comfortable nor slow!!!

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[Twister_Ken]

Canting keel, eh?

Is it meant to, or did they just build it a bit floppy?

<hr width=100% size=1>

 

[zefender]

Re: Cruiser racer

Bavaria 40 - oddly labelled 'Racer' in the application gives the following:

Capsize 2.02
Hull speed 8.1
Comfort 23

Interesting to read that even the author says of the capsize measure "This is just a rough figure of merit and controversial as to its use."



<hr width=100% size=1>

 

[Chris_Robb]

Re: Victory\'s Hull Speed

The formula gave its hull speed as 7.6. we can do 8.5 at least under engine (flat tideless water using the GPS to calibrate.) regularly do 9 knts when really pushing in F6 -7 - she won't surf - too heavy. She hardly builds any quater wake at all, unlike the Oyster 41 (S Jones one tonner) which I used to race which would build such a large quarter wake that she stuck at 7.5 knots.

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