J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Engine Bed Leak Diagnosis

Evening everyone, after a summer racing Mondial and participating in the North American's we (thanks Dave!) have managed to fix most all of the critical issues on her. However, one problem remains and I am having the damnedest time figuring it out. Underneath the engine bed, where the motor rests and you can see straight through to the relief cutout and into the bare hull there is a small but persistent leak. I had the boat pulled out three weeks ago at Muller Marine and they fixed major voids in the bedding for the shaft shaft strut, shaft log, and keel. However, to my great frustration, as soon as the boat went back into the water it began to leak again. The yard also pumped high pressure air into the engine bed to listen for escaping air around the hull, to their surprise they could not hear anything or see any bubbles. The leak itself fills the bilge completely in about two days and overflows in three, which in itself is a very annoying, but not a catastrophic issue. I think it started this spring after overwintering in our slip. Anyone have any ideas or suggestions?

That doesn't sound good.

It is also possible that the bilge pump hose has cracked and any water in the bilge is flowing in this area. Without cuttung inside the cabin sole to replace the hose the best way is to cut the old hose flush as close to the to ends of that bilge section, then snake a smaller diameter continuous hose from the bilge sump to the pump and use an adapter to mate with the pump. You can get a strainer to fit the smaller diameter hose.

If it isn't the bilge hose, check around the exhaust and also around the hull valves. Another possibility is the bolts through the hull holding the strut for the shaft. If any of these is contributing this much water, your core will be saturated.

Along the same line as Bill mentions, if the bilge hose is contributing to the leak another option is to route it to the sink drain, which is well documented here in the forum. This shortens the bilge line dramatically.

I am also curious how the air pressure test was done? What does that look like?

The yard mentioned that they removed and replaced wet core around the shaft log. Fortunately the bilge pump hose has been replaced, about three years ago if memory serves correctly. After a couple of days sitting in the EYC docks it looks like there is not nearly as much water in the bilge as before the repairs. I am going to let it set for a week or two without use, as my packing gland leaks quite a bit when under full throttle, I should probably tighten it down some more. I also had several bags of ice in the ice box, so the melt water will mask the slow leak for a day or two. Muller's thinks that there was leakage around the bilge area into the core and that water pressure was forcing the leak through the core and into the engine bed area, where it leaked into the actual bilge.

The air pressure was done by sealing off the engine bed rail, which in my boat has a hole in it to allow access to the engine rails bolts with heavy-gauge tape and then using an air compressor to pump air into the bed.

It is really hard for me to imagine how this pressure test was done in a way that could prove or disprove anything. If tape was involved, even Gorilla tape would in my opinion hold maybe a couple of pounds of air pressure at most before blowing out. Water can and does migrate through the joints in the balsa, but it does so crazy slowly and directly through the balsa even slower. My balsa drying project last spring proved that to me and that was with 15 to 20" of Hg trying to suck it through. Around the shaft log is solid GRP, it can be wet from years of saturation, but but water ingress directly through it is going to be crazy slow.

Water from the cooler, maybe. The shaft and the logs and couplings seem way more likely to my inexperienced point of view. Or there is another source from the engine itself dripping water into the bilge. There are lots of hose joints between the inlet and exhaust that all need to be carefully inspected. Not to mention the elbows that die a slow death and could be dripping into the bilge and would not show up on even the best air pressure test.