Strange Yanmar SD60 water leak

[Ndavies]

I have noticed a bead of water by the engine mounts and been trying to locate the source (salt water). No water in bilge and no leaks from engine.

So I removed an engine mount bolt and found the cradle beneath to be full of Salt Water - about 15 gallons when I pumped it out. Fortunately a slow leak - it took several days to come back. To investigate further, I made up an air fitting and put the void between the cradle and hull under about 1-2psi of air pressure to see if I could find the source of water entry.

Bubbles came from under the hull. When I looked under water, the air is coming around the sail drive., indicating the source of the leak. Surprisingly, after checking the leak detector - there is no water between the seals/gaskets. So water is somehow getting through the lower gasket and the hull and being trapped between the engine cradle - also surprised that the cradle is so well sealed/bonded to the hull that it is containing the leak.

Has anyone seen this before? How difficult is it to replace the diaphragm/gaskets on an SD60? I’m surprised I don’t see any videos on YouTube.

Btw - this is all happening after a lightning strike, which I suspect could have been the root cause as I know the lightning exited through this engine (ECM, starter and alternator all damaged by the strike)

Suggestions appreciated - I know I’m going to have to haul out to get to the bottom of this. If anyone has an idea how much work it is to replace the gaskets, or how much a mechanic might charge, this would be helpful.

Thanks!

[SV Confianza]

Originally Posted by Ndavies

I have noticed a bead of water by the engine mounts and been trying to locate the source (salt water). No water in bilge and no leaks from engine.

So I removed an engine mount bolt and found the cradle beneath to be full of Salt Water - about 15 gallons when I pumped it out. Fortunately a slow leak - it took several days to come back. To investigate further, I made up an air fitting and put the void between the cradle and hull under about 1-2psi of air pressure to see if I could find the source of water entry.

Bubbles came from under the hull. When I looked under water, the air is coming around the sail drive., indicating the source of the leak. Surprisingly, after checking the leak detector - there is no water between the seals/gaskets. So water is somehow getting through the lower gasket and the hull and being trapped between the engine cradle - also surprised that the cradle is so well sealed/bonded to the hull that it is containing the leak.

Has anyone seen this before? How difficult is it to replace the diaphragm/gaskets on an SD60? I’m surprised I don’t see any videos on YouTube.

Btw - this is all happening after a lightning strike, which I suspect could have been the root cause as I know the lightning exited through this engine (ECM, starter and alternator all damaged by the strike)

Suggestions appreciated - I know I’m going to have to haul out to get to the bottom of this. If anyone has an idea how much work it is to replace the gaskets, or how much a mechanic might charge, this would be helpful.

Thanks!

Just a thought, but are the rubber fairings that go on the hill put in by screws? Or were they once?

We had a problem that the rubber fairing originallu had a metal plate around it to hold the notoriously tricky fairings on. It was removed when we repowered, and not an issue until years later, when some sanding to put on a new rubber fairing exposed a screw hole. Went right into the engine bed, and it filled with water and leaked out the motor mounts like you describe.

[FPNC]

The fiberglass engine bed was not properly fiber glassed to the hull bottom.
It is leaking at the joint where the bed and hull bottom meet and the hull is cut out for the sail drive leg. Probably a very thin crack. The rubber seal on the outside of the hull bottom that surrounds the sail drive is not designed to be waterproof. It is only there to fair the surface and keep critters from making a home up and around the sail drive leg.