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Old 27-04-2015, 15:29   #1
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Catalina 22 Custom Keel

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if the keel (swing keel) I desire to make is a lot heavier than the original design is that going to cause her to sit too low? She's an old seventy seven and the keel is swept back. i want it to have no (foil ) which will make it relatively heavy or i could make it thinner i suppose. how do i calculate how heavy will be too heavy?
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Old 27-04-2015, 15:31   #2
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Re: Catalina 22 Custom Keel

the original design calls for anywhere from 500 to 550lbs bit if im not careful she will be lots heavier.
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Old 27-04-2015, 16:59   #3
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Re: Catalina 22 Custom Keel

Your description of your proposed design is not very informative, nor are your reasons for abandoning the original clear. PErhaps you could elaborate a bit for us... it would be helpful to all who want to come to your aid.

In general, making changes that greatly change the righting moment exercised by the ballast keel should be carefully evaluated by a competent NA. Too much decrease and the boat becomes too tender; too much increase and it may overstress the support structure in the hulls... important factors.

Jim, using Ann's computer
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Old 29-04-2015, 17:07   #4
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Re: Catalina 22 Custom Keel

weight could be relatively unchanged. The only change would be that of
the foil shape. What I know from aircraft airfoils is that drag may
effectively be reduced by a slight change in the shape of the foil. This
may all be futile given the hull being a 5.9 knot hull, but less drag is
indeed less drag and i assume that the hull speed is.indeed calculated with
the keel as a factor. I just began researching this vessel and being
homeless I can only afford a 1977 Catalina 22 that's incomplete and that
will take all my money, but I should be able to comfortably live aboard her
while I wait until I can find someone who will build my designed keel for
her. I only know what I want to do and not how to have it done. I was
thinking that since I'll have to find a way to ballast her a little till I
can have a custom keel fitted. I'm assuming that a stainless steel keel is
out of the question because stainless weighs 8000kilograms per cubic meter
while cast iron weighs 7600-7800kg for the same. yet that means a thinner
profile would be close to the same weight.
I actually meant laminar flow foil. laminar flow meansIhat turbulence is
eliminated for two thirds of the foil. Assuming that since it would be
symmetrical there would be no twisting moment to worry about. Again I just
wanted to know if it was possible to buy a custom keel and how
much it would cost since there would most likely be only about a 40%
reduction in drag (real world) and that only on the keel it may not even be
worth an extra expense. Just give a slight advantage while racing which is
why I wish to sail. Race from Miami to Key Largo. As an example
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Old 29-04-2015, 17:27   #5
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Re: Catalina 22 Custom Keel

Your Cat is probably worth as much or more than many fixed keel 24/25 footers. Maybe just sell and get what you want!
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Old 29-04-2015, 18:00   #6
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Re: Catalina 22 Custom Keel

Quote:
Originally Posted by Cheechako View Post
Your Cat is probably worth as much or more than many fixed keel 24/25 footers. Maybe just sell and get what you want!
? Do you have a cat or a Catalina? You can follow the design of the fixed keel
Catalina 22 and see if you can do some research and get a blueprint of that keel. It'll never be a super fast boat. I had many Rhodes 19s able to outpoint and out speed me in my fin keeler. I've sailed both and know what I'm doing on a race course. The wing keel was even slower.

Good luck in your endeavor. All liveaboards are considered homeless by most dirt dwellers so that's no big deal. You're just a liveaboard on a tighter budget.
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