Join Date: Feb 2008
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Raw Intake Screen
I was out on a Dana 24 last weekend motor sailing from San Diego to Dana Point. The owner was kind enough to invite me along since he had read my questions on the Yahoo Dana group site and could tell I would really like to see one (the sailing community is the best). Anyway, at one point about 3 hours into to the trip the sound of the exhaust changed to more of a "pop-pop", or stuccatto sound. About 20 minutes later the high temp alarm came on an we shut down the engine. Long story short, the "logs and frogs" raw water strainer had some kelp and a small fish in it which, once removed, restored the water flow from the exhaust to normal. The "pop-pop" sound change was likely due to the reduced water level in the muffler.
The owner decided to take his Dana to a boat yard who recommended that a screen be installed over the raw water intake through-hull. It sounded to me like the screen would act as a scoop, by configuration, and I was wondering if, when the engine was shut down and under sail, if the scoop design would force water past the impeller, into the exhaust and somehow get back into the engine. The engine is a Yanmar 2GM20F I believe. Should he close the seacock once the engine is shut off?