I felt that my tank was leaking too, so last year I pulled it out and had it tested twice. I took it to a local metal fab shop for a pressure test and again I tested it myself at home with 5 psi for 24 hours and found no leaks. My tank is aluminum from a PSC 34 1989 and was cover with a black tar on the sides and bottom. I removed most of this covering at a local self-service car wash with the degreaser and high pressure hose (before pressuring testing). I took the opportunity to clean the inside of the tank also and found it to be in supprisingly good shape. I applied two coats of an epoxy tar to the sides and bottom. Re-insertion back into the bilge was very tight and getting the holding rods back across the top of the tank was a little difficult. Oh, btw, I thought those 1.5" round tubes were aluminum and welded in place too, -- they are only pieces of PVC tubing wedged in for support. You can knock them upperward with a hammer. I also took the time, while the tank was out to clean the bilge, replace forward to aft fresh water lines and re-route any electrical wires, and of course check the keel bolts. I have to say that the Rhino lining sound good.
s/v Credence II
PSC 34 #159