T&T: Leaking Fuel Tank

[Bob Austin]

First thing you must do, is to get the fuel out of the tank--you don't want to
be caught with the bilge pump pumping this into the bay.

Unfortunately, most of the time you will eventually have to replace the
tanks..Every boat I have seen which had one tank go bad, had the second go bad
shortly.  Unfortunately the builders did not do it correctly.  The vents to
the engine room are over the tanks, so spray and water get in.  The tank is
not sloped properly to drain any water off of it, and the tank sits on a
wooden floor with no way for water to drain off.

The best way to fix tanks is to put in new floors, of marine plywood, which
are epoxy sealed and glass covered.  The better tanks, if properly made and
prepared are aluminum and they are put on plastic strips with 5200, and the
tank/strips on the plywood with more 5200.  See David Pascoe's article:
http://www.yachtsurvey.com/fueltank.htm  on how to properly install an
Aluminum fuel tank.

The biggest job is getting the old tanks out.  In my case I was able to get
the first one out mooving very little, but cutting out the floors.  The second
one was cut up in place using several dozen bimetal sawzall blades and a CO2
fire extinguisher at my side (the tanks had been well drained and
cleaned)--but precautions are better. It turned out that we did better putting
in two new fuel tanks on the port side of the boat, and actually picked up 20
gallons of fuel, which worked well, since the old steel tanks weighed in
excess of 120 lbs more.  In the second boat I had to replace tanks, the
engines had to be moved, the floors cut and some of the other wood work
disturbed.  The next owner of that boat replaced the stb tank about 3 years
after I replaced the prot tank....

There are people who have tried epoxy, bladders, welding in new tanks, cutting
out the sides and bottoms of the boats etc.  You take your choice.  My opinion
is to put the new tank in from the engine room..

Bob Austin