Conversation went south

[Capt Dick Dean]

A local 31 fbc is getting a re-man std engine and I stopped by to see the progress. But they also cut the top of the gas tank off. It was right next to the boat.. Why, I asked. The tank was failing from ethanol. The plan is to build a new alluminmin tank and put it inside the now open old tank as a craddle. When they were about to cut the top off, they filled it with water for safety. The tank started to leak water into the hull when it was half full. What the hell is going on??

Now this is the point. The tank's baffl;es are stainless and were riveted into the bottom, top and sides. The rivets corroded away. The water leaked out the rivet holes into the bilge when fillng the tank When the boat was built and the baffles were installed, the factory fiberglassed over that seam. Looking at the cut off top, you can see the bump where the rivets were fiberglassed over. It looks like a mini speed bump. This boat is a 1966. My boat is a 1972 and doesn't have the bumps. I checked this right out on my boat.





Why didn't the gas leak into the hull when the owner fueled up? Good question but a simple reply. The owner never took on more than 50 gallons at a time. Boat never left the bay, just went across the bay and back.

The rivets failed 'cause the tank was never filled ... for thirty some yrs.

[Rawleigh]

I have a 66, and mine has molded in ribs that the baffles seem to be recessed into. I don't think there are any rivits (I hope)!

[craig mac]

The yard I use for fiberglass work-RAYBO MARINE (Lindenhurst,,NY)-is currently working on a gas tank out of a 33 Bertram----baffels are monel and rivited and glassed over----not sure the year of boat, but i believe all were made this way.

[Peter]

I had an old car like that for awhile. The tank failed at the mid-point height seam. It took a couple of long weeks to get a replacement tank and the time to install it. In the meantime,I just never took on more than about 3/8 of a tank of gas. The stupid things one does in one's youth!

I have a 1976 26 FBSF. It has the rivets. So far it isn't causing problems.

Could it have been that the rivets were still in place and stuck in the old tank well enough to prevent leaking until the heavier (than gasoline) water was run in causing a slightly greater pressure, thus exposing the weakness and starting the leak?

How did the new tank inside the old shell work out? If I do wind up doing mine it would likely be the same way because the old tank is so nearly integal with the stringers and bulkheads. I figure it has to add a lot of stifness to the hull like that.