Sea Ray

I have seen this issue on 2-3 boats here. In all cases, the leak into the area between the compartment floor and the hull either began with or was found to be a pin hole in the front or rear wall of the bilge sump. If you get water under the center compartment on a 390EC, it will work its way up thru the bottom of the plywood board the water tank sits on. There are aluminum angle brackets holding the front wall of that compartment in place and water comes up thru the bottom screw holes. Once the area below the water tank is full, water rises up thru the floor of that compartment and your water tank then sits in water until it corrodes.

The bilge sump in these boats is formed by V-shaped blocks of wood glassed to the hull, then the flat part of the bilge floor built on top of the block. The sump walls are formed by hand and can get air pockets in them. Over time, bilge water can enter the air pocket and find its way to the hull under the floor. Once the water gets to the hull, it can run forward or aft along the inside of the hull. So even if you find water under the cabin floor, it can easily have originated in the bilge sump.

Unfortunately, closed cell foam Sea Ray sprays under the cabin and bilge floor as a sound deadener will eventually retain water after it has been soaking for a while. It takes a long time to get the water out. You can mount an inspection plate in the floor of one or more compartments, at a low point in the hull (when the boat is in the water) then remove the cover and use a Shop-Vac to periodically remove the water that has drained out of the foam.

This is one excellent reason to keep your bilge spotless. If your boat has an oily bilge from spills, leaks, etc.., then any water that leaks from the bilge sump into the hull will have oil in it and your entire boat will eventually smell like oil.

Not a pretty picture, but it is what it is...............

Thank you for the great info.  It is going to help us in our problem. 


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Welcome to Mr Webster's wealth of knowledge! He pretty much knows everything...

We had 1996 with a small nick in gel coat near bow thruster. The water wicked into the storage compartments under the cabin--- filled a pail once a week. Fixed nick on hull and water stopped.

Is the transom all fiberglass or does it have wood sandwiched between fiberglass on the 1989 express cruiser?

What Express Cruiser? ......Generally yes. Sea Ray uses a piece of plywood in the transoms, not as a core but as a way to mount things to the transom. On my 390EC the plywood was only near the top and did not extend all the way to the bottom of the hull,

It's a 390. Thank you. I have a tiny leak where the anode mounts and was worried that it may get into the wood.

You do need to repair the leak fairly soon. Even though there may not be plywood that low on the transom, a leak there can easily cause a delamination in the fiberglass layers.

What usually happens is whoever changed your transom zinc did not hold the jam nut against the transom when tightening the outside nut and crushed the transom by over tightening. The resulting delamination can quickly grow to where you have a sizeable repair.

The fix is easy, haul the boat out of the water and remove the B-12 zinc and all the mounting hardware, then grind away the exterior until you get to dry fiberglass. Next, fill the hole with glass cloth and resin (do not use a filler putty) and redrill the holes for the zinc studs. Use 3M 5200 and reinstall the stainless steel sleeves and then the bolts. Use plenty of 5200....it is easier to clean up a little sealer than to redo the repair. Tighten a washer against with a nylon inserted lock nut.

In the future, be sure whoever changes the zinc uses an open end wrench and hold the nut against the transom stationary then loosen the nut on the outside of the zinc

Will do. Thank you for your time.