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post #1 of 13 Old 02-07-2007 Thread Starter
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Cutting off keel!

I recently bought a 25' Yamaha fin keel sailboat and have been sailing in FL to get ready to go to the Bahamas. Question is with the 5'5" draft I have been having trouble touching bottom and I'm considering cutting off maybe 10"-12" from the keel and maybe add a little weight to make up for this. Good idea? Thanks in advance!
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post #2 of 13 Old 02-07-2007
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This is probably not a good idea... and one that you should talk to a naval architect about before proceeding. The keel serves two important functions, first it acts as a foil to prevent/reduce leeway, and second, it acts to provide a righting moment to compensate for the pressure of the wind against sails.

Adding a bulb to the keel might work to compensate for the shortened keel, but it would probably require more weight than the mass removed, and would probably affect its function as a foil.

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post #3 of 13 Old 02-07-2007
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Greg,

I am not familiar with that particulair boat, but as a non-marine architecht, here you go:

Bad idea. Most boats are designed with a specific keel for that hull design for that sail plan. Cutting off some of your keel could result in a tender boat or winward performance or both - and compromise your safety.

THose are my thoughts though.

- CD
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post #4 of 13 Old 02-07-2007
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Several years ago one of the big glossy mags had an article about a guy who did just that, and added a bulb to the end of the keel to make up for the loss in weight. he did work with a naval architect. If you check www.marsmetal.com they may have that article on their site. They also can help you with the project, which, as others have said, is not to be taken lightly. Mars advertises quite a bit, too.

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post #5 of 13 Old 02-07-2007
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..... where do you want to go in the Bahamas?

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post #6 of 13 Old 02-07-2007
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I can see why you want to do it. The damn thing is made of lead and so it slows the boat down not to mention it gets in the way when you are in shallow water. That tongue in cheek aside, did they offer your boat in a shallow draft version? If so then the engineering has already been done. My boat was produced in a centerboard 4 foot draft version and a 5 foot version. I own the centerboard version but if I were going to convert I would just get the specs from one of my sisterships.
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post #7 of 13 Old 02-07-2007
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Mars Metals are the folks to ask. They can fabricate a bulb that will correct your loss or righting moment, but as others have said you are also losing the foil and that has to affect your pointing ability. The folks at Mars might be able to tell you how to check on that, or recommend a naval architect who could run some numbers to give you a better idea.

If you really want to get into shoals...it might be better to look at selling the boat and getting a centerboard boat instead.

Also bear in mind, once you circumsize your keel, the resale value of your boat may also get chopped down.
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post #8 of 13 Old 02-07-2007
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I have recently purchused a potter 19. The centerboard(which weights about300 pounds ) was taking out and replaced with 600 or so pounds of lead and put in the hull.
I havent"sailed" the boat to much yet. however we have moterd the boat quite abit and it feels very stable and seaworthy. the centerboard was replaced with a marine plywood which was fiberglassed over.
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post #9 of 13 Old 02-08-2007
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greg...you don't NEED to reduce your draft to see 99% of what others in shallower draft boats see in the Bahams. I don't see the point of the work or expense.
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post #10 of 13 Old 02-08-2007
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This has been done quite a bit in my club, generally on bigger boats like C&C 45s that draw (7-8ft?) they get a bulb from Mars and bolt it on. They are located in Toronto which is just 3 hours from us.

I would not do it and it is expensive not to mention a lot of work.

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