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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Catalina 25 Stability

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skrenz
Captain

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USA
351 Posts

Initially Posted - 05/11/2012 : 00:49:06

Does anyone know if there is a stability curve calculation anywhere for the Catalina 25s? You know, those sine wave diagrams that chart righting moment against heel angle. Perhaps even for a swing keel 25? (No jokes about what happens when a swing keel is upside down please

) I suspect that it is pretty high but it would be interesting to see.

In the same vain, did Catalina ever publish any polar curves for the Catalina 25? If so, how can I get it?

Steve Krenz
`Elan
1978 SR/SK #482
Santa Fe, New Mexico

Edited by - on

Prospector
Master Marine Consultant

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Canada
3159 Posts

Response Posted - 05/11/2012 : 07:35:51

All I know is it will self-right even if you have the cabintop winches in the water and are knee-deep in water in the cockpit.

Edited by - on

JimGo
Admiral

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USA
962 Posts

Response Posted - 05/11/2012 : 07:52:42

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Prospector
 All I know is it will self-right even if you have the cabintop winches in the water and are knee-deep in water in the cockpit.
<hr height="1" noshade id="quote"></blockquote id="quote">

You forgot "...not that this has ever happened to me..."

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 05/11/2012 : 07:54:57

It will also right itself rather smartly when the spreader tip nears the water. I've tested this on more than one occasion.

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Prospector
Master Marine Consultant

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Canada
3159 Posts

Response Posted - 05/11/2012 : 08:02:29

I didn't check the spreader tips Don, I was too busy retrieving the gas can before it floated away. I'll put that on the to-do list.

On a more serious note - the self-righting ability of the boat is seriously compromised if the dumpster fills with water. Secure the latch before heading out in heavy weather. A small carabiner works well and still allows quick access if you need to retrieve a fender or whatnot in a hurry.

Edited by - Prospector on 05/11/2012 08:04:17

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 05/11/2012 : 08:20:11

I can't help if you want hard numbers for some purpose, but laying a swinger over far enough to take the rudder completely out of the water just results in rounding up and getting back on her feet. Really ugly waves could get you in trouble, but you would know that you were someplace you shouldn't be long before it became critical.

Edited by - on

skrenz
Captain

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USA
351 Posts

Response Posted - 05/11/2012 : 09:18:54

I realize that this may sound like an esoteric request and I am not questioning the stability of this hull design. But it would be interesting to be able to compare an actual stability graph for a boat I know and understand to stability graphs for other designs. This design has been around for a long time. I would think that somewhere along the way such information would have been generated. Would Catalina know? If so, how does one go about asking them this question?
BTW, it is also very useful to know the 1 degree righting moment when thinking about replacing a mast or rigging, etc.

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Prospector
Master Marine Consultant

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Canada
3159 Posts

Response Posted - 05/11/2012 : 10:08:20

Sorry Steve - can't help you much, but I know there were some convos about righting moment with a person up the mast a while back. That conversation ended up with some technical info in it, but I can't remember how detailed it got.

CTY is very good about putting folks through on the phone. Give then a call.

Edited by - on

Steve Milby
Past Commodore

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USA
5902 Posts

Response Posted - 05/11/2012 : 10:23:43

Is this what you're looking for? http://www.wb-sails.fi/news/SailPowerCalc/SailPowerCalc.htm

For those interested, there's a good explanation of stability curves here. http://sailskills.co.uk/Stability/sailskills_stability_stability_explained_righting_GZ_curves.html

Polar plots for a C25 have been sought here for years, but I don't recall anyone ever finding them.

Edited by - Steve Milby on 05/11/2012 10:53:14

Stinkpotter
Master Marine Consultant

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Djibouti
9080 Posts

Response Posted - 05/11/2012 : 10:43:28

I think I found a polar chart for a similar boat on the web once--perhaps an older 25' Hunter. It seemed to me the differences would be minimal... (I wouldn't say that about the newer Hunters.)

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