Main fuel tank leak

[Alan N Crichton]

My vessel is fitted with a 30l day tank which is filled from the main tank in the keel. I purchased her from the builder one month after launching however I whenever I am on a starboard tack at +15deg of heel I find diesel in one of the port compartments under the floor boards. After months of searching I finally have establised , by pressurising the tank, that the leak is somewhere near the top one third of the tank. Upon draining and opening the hatch into the main tank I find that the GRP hull serves as the containment vessel. The surfaces are coated with what looks like thick blue gelcoat.

Suggestions as to what I can recoat the inside of this tank with to ensure leak free containment ?

I have attached two pictures for clarity - A view down into the first section of the tank showing the inside contour of the hull and a view into the second tank.

[Chief Engineer]

If you purchased this boat from the builder, why are YOU repairing it?

[Inthewind]

Maybe you could fill the compartment that the diesel is leaking into with some kind of liquid, perhaps water mixed with a colored dye. That way you may be able to determine exactly where the leak is. I would say you would have to grind the gel coat off down to the fiberglass. Then re-glass and then re-gelcoat. Good luck.