Just Baffling - Leak in Engine Compartment Basin

[Snowgoose71]

I have a 1998 Beneteau 352 and there is a VERY slow and small leak in the basin under the propshaft. It is not the shaft/shaft seal as both have just been replaced. Additionally, the exit point where the strut/cutlass bearing reside has been redone with epoxy/5200.

I know about the Beneteau memo and the skeg. That is why the epoxy was redone to prevent water coming from there.

Here is the situation. While at the slip there is no leak or very little maybe an ounce. If the boat is taken out and under power for a while then the next day there is more water (about 12 - 20 ounces). I've paid alot of money to try to remedy this and even the boatyard doesn't know for sure what the problem or where the water is coming from.

Anyone else have any ideas or experience similar problem?

Thanks,
Robert

[Deep Blue Water]

Where ever the leak is, it sounds as if it flexes slightly when under way, allowing more water in. Have you had the hull checked for cracks?

[Snowgoose71]

Henry - haven't had it checked (at least that I know of). I've had boat hauled 3 times....first to replace the shaft/shaft seal because they thought it was leaking from the seal. Second time they gelcoated all around the basin area trying to prevent the leak. The third time was to reseal the exit point where the metal strut is located thinking the leak may be coming in at that point and making its way through the skeg.

I probably will haul at end of year and can request them to look for cracks....

[Deep Blue Water]

There's a process we use in motorsports to check for cracks, for example in suspension components or wheels. Here's an idea, this may help:


https://www.pegasusautoracing.com/gr...upID=CRACKTEST


There are more expensive processes but if you can get the boat out of the water and let her dry out, this may work.

[Snowgoose71]

Thanks again....the other suggestion from Beneteau/boatyard was perhaps to replace the fiberglass sterntube that of course goes through the skeg. I've been told that is not an easy thing to do....but if the sterntube is cracked then I suppose the water could be leaking from that into the skeg area and then making its way up to the propshaft basin.

[C420sailor]

Same thing on our 361. Seems like it fills to just below the shaft seal and stops. Weird.

[Snowgoose71]

Hey C420 - that is same with mine. Just under the prop shaft seal and then stops! Of course as I said in original it only does that after I've been out...come back to the slip wait until the next day and vaccum water out.....after that then it stays dry until I take it out again!!!

Have you done anything to try and diagnose/fix or just deal with it?

[C420sailor]

I just deal with it. It seems like when it happens, a thin film of pink diesel always appears on top.

That said, I did notice that someone previously put sealant around the exterior of the stern tube that is falling off. I’m in the middle of doing the bottom, so I’m going to re seal it. We’ll see if that helps.

[Snowgoose71]

Yeh I tried that as well....ground what was there all out and reapplied with 5200. Seemed to help but didn't totally fix it.

[LittleWing77]

Originally Posted by Snowgoose71

Here is the situation. While at the slip there is no leak or very little maybe an ounce. If the boat is taken out and under power for a while then the next day there is more water (about 12 - 20 ounces). I've paid alot of money to try to remedy this and even the boatyard doesn't know for sure what the problem or where the water is coming from.

A long-shot, I know, but have you gone below while motoring and panned around the engine compartment with a flashlight and/or the shaft to see if you can trace the source of the water ingress? If it only happens while motoring, you might be able to catch it when those flexing conditions are active...

LW77

[C420sailor]

Just to confirm, you removed the tank and checked for cracks underneath the tank/over the skeg/tube?

[kapnd]

Rudder shaft seal above the waterline?
Little Wing suggested checking it out underway.
If the seal is above the waterline, it possibly never got properly adjusted, as the only time it’s wet is when underway, and water is forced up it.

[Sailor_Al]

My engine mounts were loose. I seen the lock washers were expanding. The dipless seal misted the back of the engine with a little bit of salt water that settled into the engine bilge. A little rust got started on me.

[chris14679]

get it all very dry (hair dryer or fan heater). Put dry paper towels everywhere, under or touching anything which might leak. Monitor them closely. First wet spot identifies your problem.

[EngineerRetired]

Dry up ALL the water and surfaces. Dust everything with a light coating of flour. Use drive for an acceptable time, water source will be self evident in the flower dust.