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post #1 of 13 Old 09-17-2013 Thread Starter
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Smile Keel weight

Hello
I am thinking about building a new keel for my 20 ft long sailboat, but I cannot figure out, how to decide the weight of the keel, are there any kind of mathematic formulas?

Rasmus
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post #2 of 13 Old 09-17-2013
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Re: Keel weight

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Originally Posted by Qwunununu View Post
Hello
I am thinking about building a new keel for my 20 ft long sailboat, but I cannot figure out, how to decide the weight of the keel, are there any kind of mathematic formulas?

Rasmus
Why do you want to build a new keel?
What is wrong with the old?

The keel have more than one function so there is not one simple formula.
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post #3 of 13 Old 09-17-2013 Thread Starter
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Re: Keel weight

Hello Knuterikt
I want to build a new keel because I am about to make my boat more like a race boat, and the person that builded the boat, did not made it really good. He made the keel in lead from top to bottom, and then I was thinking that it would be better with a torpedo keel, were all the weight was so low as possible.

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post #4 of 13 Old 09-17-2013
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Re: Keel weight

This is designer and engineering territory.. the hull and reinforcements would have been designed for a certain weight/righting moments of the original keel.. attaching a heavier keel could cause issues. I think you need to tread cautiously here....
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Re: Keel weight

Hello Faster
I would not make it heavier, but lighter and deeper, to make the boat lighter also.
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Re: Keel weight

Lighter and deeper could still put more stress on the structure, 'depending'.... Do you have the skills to know what shape/foil to use? to maintain (or improve) the center of lateral resistance? This is all pretty technical stuff, - if you're confident you could have some fun trying something new. But don't be surprised if there's no dramatic improvement (or worse) without some input from the professionals.

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post #7 of 13 Old 09-17-2013
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Re: Keel weight

You might start with carefully matched scale models before working on the big boat.

- Jim
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post #8 of 13 Old 09-17-2013
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Re: Keel weight

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Originally Posted by Qwunununu View Post
Hello Faster
I would not make it heavier, but lighter and deeper, to make the boat lighter also.
With all due respect, designing the shape, weight distribution, and supporting structure for the keel is one of the more complex design and engineering aspects of designing a boat. The quote a above suggests you probably do not have an adequate understanding of the way the loads work to safely design a keel and its attachments.

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post #9 of 13 Old 09-18-2013 Thread Starter
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Re: Keel weight

I am not going to build it all alone, i will try finding some professionals, that could help designing and build the the keel so it stay in place and do not brake something.
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Re: Keel weight

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Originally Posted by kallis2222 View Post
Dude its totally work of the engineer whose tell to you that how much feet keel is suitable for your boot..Now i discuss with my friend who is the owner of the boot and tell to you after that...
Sorry but I do not understand what you are saying Kallis2222, could you try explain it in another way?
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