Mystery Leak

[L27]

I have a Sea Sprite 27/28 with a delaminated and wet lower main bulkhead. I can't for the life of me figure out how it's getting wet.

It's a rainwater leak while the boat is on the hard. This peculiar leak has me really scratching my head. I have come to the conclusion that while a boat is blocked, water pools in places that it wouldn't normally pool while on the mooring- but that still doesn't come close to me finding the source. There are no water trails down the bulkhead, and nothing is wet above the pooling water anywhere.

The main cabin bulkhead this winter has been wet on the bottom, along with the cabin sole at the bottom of the bulkhead. The bilge has three levels that all connect. Forward of the bulkhead in the head/shower is a grate with a drain that leads aft. That area is dry. Aft of the bulkhead is an opening to the forward portion the bilge, as seen in the photos. This is damp but doesn't look like water has been streaming through it. The furthest aft portion of the bilge has an inch of rainwater in it.

The deck hatch slightly forward of the bulkhead does not leak, and the one aft is also sealed. The portlights do not leak, and the chainplates are dry. I laid paper towels around areas I thought the leak could be coming from, and possibly draining down to the bottom of the bulkhead. I then checked them after it rained and they were dry.

When I bought this boat, there was some staining and slight delam on the bottom of the bulkhead showing a history of water leaking, but it never leaked like this during my ownership until this year. The delamination has since gotten much worse, and I'll need to repair it, but I've got to get it dry, and the leaked stopped first.

Here are a few photos. Any insight would be incredibly helpful.

 

[Ken Cross]

Is that near the tabernacle? One test you can try is to pressurize the inside of the boat with a shop vac, leaf blower, etc. Then use soapy water on the outside and look for bubbles. I haven't tried this, but I've been told it works well.

Ken

 

[dlochner]

Several thoughts.

First, look for a leaking port on the starboard side. the water might run down the cabin liner out of sight until it gets to the floor pan. Could also be a stanchion or other deck fitting. The leak can be very far from where it shows up.

Make sure the boat is blocked properly. It doesn't take much, just a couple of degrees out of level and water will pool where doesn't normally pool.

The mast step is another possibility. The water can run down between the headliner and the cabin top. Also any cable entry points on the deck or in the mast step.

Also look at the dorade box.

When boats are on the hard their shape changes. It could be those small changes are opening up leaks that are not normally seen when it in the water.

 

[rgranger]

Grab a 6 pack.... turn on the water sprinkler and hang out inside your boat for a bit

 

[capta]

Is this bulkhead structural for anything exterior to the boat, like a mast step or chainplates? Water can run down inside these plywood bulkheads with no exterior evidence until it reacher a place it can come out easily. Plywood can also wick water uphill a tiny bit, making the entrance hole for the water below the not the highest point in it's travel.
Colored food dyes can help identify a point of ingress.

 

[DArcy]

Have you tried reaching out to other Sea Sprite owners? I'm not familiar with these boats but I was intrigued by the pictures so I looked them up. There are 2 currently posted for sale on Yachtworld, both appear to be very well maintained but both have some amount of water damage on the floor in the area you are having trouble with. I know from my boat, water travels a LONG way inside before it gets to the bilge. Fiberglass headliners are wonderful for a clean interior but are great at re-directing and hiding leaks. My toe rail leaks and finds it's way to a similar location on my boat. I fixed the starboard side but now the port toe rail needs to be re-bedded. It could be coming from any cabin top deck fitting, cable entry, chain plates, toe rail...