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post #4 of Old 03-30-2013
msmith10
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Re: Keel Help!

I'm not a naval architect and I'm not sure what you mean by stability, but I'll give it a shot:
There are 3 movements the boat can make while sitting in one spot: roll, which is the boat rocking from side-to-side; pitch, which is the boat going up and down in the front (bow); and yaw, which means the front of the boat going from one side to the other.
If by stability you mean continuing in a straight line (tracking), a full keel is better. If you mean preventing the boat from rocking side-to-side (rolling), it's a matter of getting the maximum amount of weight the farthest down underwater- either full or fin could do this but typically a long fin with a heavy bulb on the end would be the approach. If you mean stability at anchor, so someone inside could cook in your floating kitchen, a full keel will keep it pointed into the wind better while a fin keeled boat may tend to yaw more (the front will head from one direction to the other). Again, though, a long deep keel with a lot of weight at the bottom will do better to prevent rolling.
I'm not sure about pitching - I would think that a fin keel with weight concentrated in the center of the boat would be more prone to pitch than a full keel spreading the weight more along the length of the boat.

Did you choose your dimensions? 8' is very narrow for a 45' boat- she's going to sit very low in the water and won't have much form stability (that's another topic).

Mark Smith
1977 C&C 30 Mk 1 hailing from Port Clinton, Ohio

Last edited by msmith10; 03-30-2013 at 05:28 PM.
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