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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

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tom
1st Mate

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USA
52 Posts

Initially Posted - 11/25/2002 : 18:58:49

Regarding the Catalina 25 the Capsize screen is 1.99 and the displacement to lenth ratio is 176.5 and the sail area to displacement is 22.31. Can anyone tell me what these mean and are the numbers good ? For example is a Capsize screen of 1.99 good ?

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 11/25/2002 : 23:00:05

Hi Tom... I'll relate what I can remember from what I've read about the capsize ratio (presumably the same as capsize "screen"): Under 2.0 is considered "adequate" for a coastal cruiser but would not be recommended for blue water passagemaking, for which the ratio should be considerably lower. At about 2, you can expect the boat to be able get you through modest coastal storm, but you would be better off seeking shelter. As you go above 2, you have to question the boat for coastal cruising and think of it more as an inland boat, or at least one you won't use to challenge Mother Nature.

The other ratios help predict the performance of a boat in relative terms, and generally quantify the compromises that were made in its design. Lower displacement to length suggests higher performance and less comfort--in ride and accomodations. Sail to displacement suggests the tenderness and performance. Comparing boats, you can see from these ratios which direction the designer went. One number is "better" than the other only as it relates to the characteristics you desire.

Dave Bristle - 1985 C-25 #5032 SR-FK-Dinette-Honda "Passage" in SW CT

Edited by - dave bristle on 11/25/2002 23:10:00

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matsche
Captain

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USA
280 Posts

Response Posted - 11/26/2002 : 07:17:54

If you want to see how the Cat 25 stacks up to other boats with regards to various performance factors like these, check out http://www.image-ination.com/sailcalc.html . Unfortunately, the web site doesn't give much of an explanation for the different factors.

John Matsche 1985 Cat-25 TR/FK
e-mail: matsche@mindspring.com

Edited by - matsche on 11/26/2002 07:20:43

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pwhallon
Admiral

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USA
694 Posts

Response Posted - 11/26/2002 : 07:23:11

Hi Dave,

Would the capsize ratio change depending on the keel of the boat? Wing, swing or fin.

Does a fin keel model have a lower center of gravity? Are the different keel weights designed to keep the center of gravity the same on each model?

Is capsize ratio the same as righting moment?

Why won't Duane let me "secure the main brace"?<img src=icon_smile.gif border=0 align=middle>

Thanks,

Paul

Edited by - on

Derek Crawford
Master Marine Consultant

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USA
3324 Posts

Response Posted - 11/26/2002 : 10:40:52

Paul - the other explanantion for "splicing the main brace" is that it was such an important line that it was almost never spliced, just replaced. So getting a double tot of rum was as rare an event as "splicing the main brace". Typical sailor humor!
Derek

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pwhallon
Admiral

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USA
694 Posts

Response Posted - 11/26/2002 : 16:10:18

Hi Derek,

Being married since 1984, I can tell you that I do know one nautical term.

Something about being in the dog house!<img src=icon_smile_blackeye.gif border=0 align=middle>

Paul

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ronrryan
Admiral

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USA
561 Posts

Response Posted - 11/26/2002 : 20:44:31

I do believe the main brace was the main forward stay to the main mast, amd the largest line in the ship, and splicing it was the toughest markinespike job ever for the bosun and his mates. No wonder they got an extra ration of liquid happiness when done. Don't we hqve it easy, though? Godspeed and Happy Thanksgiving, ron srsk 1981 "Orion" SW Fl

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 11/27/2002 : 12:00:30

<BLOCKQUOTE id=quote><font size=1 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>
Hi Dave,

Would the capsize ratio change depending on the keel of the boat? Wing, swing or fin.

Does a fin keel model have a lower center of gravity? Are the different keel weights designed to keep the center of gravity the same on each model?

Is capsize ratio the same as righting moment?
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
Hi Paul... I pretty much said as much about capsize ratios as I think I know. <img src=icon_smile_blush.gif border=0 align=middle> The righting moment is a force that is probably used in the calculation of the capsize ratio (screen?). I think the ratio takes into account various dimensions and weights.

Regarding the various C-25 keels, the wings I've looked at, while shallower than my fin, certainly look like they have enough mass down low to make up for the leverage difference. I haven't heard complaints that any of the three C-25s is significantly more tender than the others, so I suspect they got the righting moments pretty equivalent on the three.

Watch those double-tots, everyone... A happy and safe Thanksgiving!

Dave Bristle - 1985 C-25 #5032 SR-FK-Dinette-Honda "Passage" in SW CT

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