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post #1 of 5 Old 03-02-2009 Thread Starter
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Question keel mods

I have a 40 ft gaffrigged motor sailer, a converted fishing boat built in 1934 with a full keel ,
is it possible to extend the keel downward and bolt ballast to this instead of having 1.5 tonnes under the floorboards
will this extra draught affect the handling , and/or reduce sideslip
[currently looking at extending dowm 250mm, full length ]
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post #2 of 5 Old 03-02-2009
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It's certainly possible to do this - but not without some really good advice from a qualified Naval Architect first. If the boat isn't designed to carry the weight down there, you could really stuff up your day...

If the boat is that old, it's probably a one-off. Try to locate the designer/design house and ask them. If not, call a surveyor.

A bad day on a boat beats a good day in the office
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post #3 of 5 Old 03-03-2009
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I'd second getting a naval architect to look at it.. and go over how the new ballast would be attached.


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post #4 of 5 Old 03-03-2009
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If your boat is a 1934 motorsailor and you want to head upwind and not have too much leeway, starting the engine will probably be a lot cheaper and easier than deepening your keel by 25 cm by adding a shoe of some type to the keel. Adding that much wetted surface would likely slow down the boat a lot (perhaps by 2-or more knots?), to say nothing of the ability of the now elderly structure to support the weight and stresses involved. If you're not happy with the boat you have, perhaps you need a different boat. That's what the changes you're talking about seem to indicate.

Last edited by paulk; 03-03-2009 at 08:02 PM.
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post #5 of 5 Old 03-04-2009
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You might consider leeboards. Probably easier to install and would work as well as a keel shoe. There may be centerboards from other vessels that can be modified.
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