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Sunday, August 27, 2006

Cockpit Drain Replacement

Well, the existing (temporary?) cockpit drains that were installed by the Westsail's previous owners were replaced this weekend. Besides being the wrong type of fittings (plastic mushroom thru-hulls), they were bedded with silicone. I suspect they were temporary, but given what else we found in this boat one can't be sure. Anyway, they were leaking, so I decided to replace them before the rainy season hits. And, following the rule "do it right, or don't do it at all", I installed permanent drains. The old drains came out quite easily. Choice of Drain Size The rule of thumb is to make the cockpit drains as large as possible. If you take a wave and fill the cockpit with water, you want it to drain as fast as possible. With a "center cockpit" we have less of a chance of filling up than with an "aft cockpit". Still, we want to maximize drainage. Two inch diameter hose for drains would be ideal, but all two inch drains/scuppers I could find were too big for the "wells" molded into the cockpit floor. The largest I could find that would fit were one and a half inch diameter hose size. Choice of Material Traditional materials are bronze and stainless steel. Newer modern materials are nylon and marelon. Nylon is pretty much discouraged these days as UV will attack it, turn it brittle and crack over the years. Marelon is a "UV stabilized glass reinforced resin" material. Very light, very strong. It will bond with adhesives better than metals. Marelon can also be used for underwater fittings, though I personally am not comfortable with that (yet, I may be convinced later, bronze vs marelon seems to be a big debate in the boatbuilding community). Above the waterline they are perfectly suitable. Forespar Marelon Cockpit Drains We went with Forespar's flush mounted marelon cockpit drains at less than $20 each. The holes were routed with a 45 degree bevel and the drains were bedded with 3M 4200 adhesive/sealant with a backing plate made of Coosa board. The cockpit has three wells on the floor "molded" from the factory, plus there was a "pad", with no hole, in the portside aft corner that looks like it was intended to have a drain. So four drains total were installed. For now, as with the old drains, they all join together and drain through a garden hose out the stern tube. Installing and connecting them to thru-hulls comes later.