Many steel boats are problematic because they were not prepared correctly in the first place. If the interior
was blasted, then had proper epoxy
coatings applied to it it will give few problems. Foaming is less than desirable for a couple of reasons. First, when it burns most applications will give off cyanide gas. Second, it can hide improper steel preparation or welding technique. It does have the advantage that it will generally eliminate condensation
, so no water, no corrosion
Delfin has 13 years on her coatings and other than small exterior dings I fix with an airbrush the maintenance
is significantly less than my FRP sailboat with a bit of wood.
Some Dutch boats, especially those built by yards like Vripak, have proper coatings, then balsa covered with tar to prevent condensation
, then fiberglass
batts over that. They will last longer than you will.
To accomplish the same effect on Delfin, we lined her with acoustical cork over Quietship, which is basically a sound deadening compound that goes on around 10 mils thick and provides additional protection from condensation. This was sprayed over a proper base of Ameron. Fiberglass
batts over that and she is completely dry with zero condensation. Rust could occur, I suppose, but I just don't know how.
So my two cents is that if you can find a steel boat built by people who build steel boats, then verify how she was painted and what the plan was for elimination of condensation, you can cross fretting about internal corrosion off your list of probable worries. External maintenance is pretty simple, again assuming the people coating her knew what they were doing.