Removal of Steel Fuel Tank

[Mike Sibley]

I recently removed the 50 gallon steel fuel tank from my 1979 Pearson 365 in preparation for the installation of two replacement tanks.  Of course, one alternative is to pull the engine and remove the old tank through the passageway.  Then it can be replaced by a single tank of equal size, installed through the passageway.  After receiving an estimate for this approach, I decided to cut the existing tank in half myself, remove the halves through the cockpit lockers, and replace it with two tanks, each half as wide as the original.  This seems to be a project that many 365 owners have already tackled or are facing now, so a brief description of the removal process is provided.  Actually, it is not as big a job as I had feared.  The removal of the old tank can be completed by a single person in a single day if you are well organized.

The first job is to remove as much fuel from the tank as possible.  Disconnect the fuel hose where it attaches to the primary fuel filter and use an electric fuel pump or a hand pump to transfer the fuel into five gallon fuel cans.  It is best if the tank is less than half full before beginning.  (Due to the shape of the tank, there are only about 20 gallons in the tank when the fuel gauge reads half full.)   

When I emptied as much fuel as I could, I poured in a gallon of degreaser and a gallon of water.  I know that diesel is less easy to ignite than gasoline, but I didn't want any unpleasant surprises.  I then siphoned out a small amount of the mixture and tried to ignite it with a BernzOmatic torch.  It failed to ignite, so I began cutting.

The first step is to cut out two rectangular sections on each side of the tank.  The baffle runs perpendicular to the centerline, so one section is in front of the baffle and the other is aft. Cut these sections as large as possible to afford maximum access to the inside of the tank.  I used a reciprocating saw with a heavy duty bimetal blade with 14 teeth per inch.  The tank is .125 steel, but cutting goes quite fast.  Once the sides are opened up, the remaining mixture can be removed with a plastic scoop or a cup and a few wads of paper towel.

The baffle is thinner metal with three holes in it, so it is easily cut.  Cut to the center hole from each side of the tank.  Due to obstructions and cramped space, the front and back walls of the tank are most easily cut with the saw inside the tank. Again, start from each side and cut to the center. 

Once the tank is cut in half horizontally, the top half is easily removed, although it is heavy.  The bottom half is a little trickier for one person to get out, but it can be done.  After removing the tank, be sure to vacuum up all the small metal pieces so they don't leave rust spots.  I have some pictures if anyone is interested.

After removal of the bottom half, I inspected it carefully to convince myself that it was a job that needed doing.  Although there clearly were some spots with internal rust, no place seemed on the verge of leaking.  Of course, there was an enormous amount of crud in the tank.  Would I still undertake this project if I knew then what I know now?  I think so.  I am looking forward to nice clean tanks and plan to install the necessary systems and take the necessary steps to keep them clean.  Peace of mind has a high value when far from shore.

[SV THIRD DAY]

Ah....as I'm sitting here anchored inside the breakwater at Santa Rosilia in the Sea of Cortez Mexico...I can look back and remember when I cut my tank out and replaced it with two smaller alum tanks...ah...the memories!

Keep us udated on the install Mike...ripping things out of a boat is sometimes harder than putting the new things back in!

Rich

[Mike Sibley]

I now have two new aluminum tanks ready to install, but am unsure of the proper installation method.  If anyone has replaced their old tank with two aluminum tanks, please describe the platform you created to support them and the steps taken to prevent crevice corrosion.