Square tank (mostly pre. WWII) or molded tank (after WWII)?
Square tanks are easily braced so you can support areas that are
not damaged while you work on a spot that is. The shape’s of
post war tanks makes that difficult. Post war tanks are thinner
and you can easily distort an area that isn’t damaged while
attempting to repair a spot that is so pay attention to the whole
tank as you apply air. Turning down the air at your compressor
and having another regulator in line to the tank gives you good
control so you can watch the tank as you increase the pressure.
My experience is mostly with square tanks. My success using
air is nothing to brag about but I keep trying. For me, the type
of dent and its location determines how successful the end result
will be. Some tanks will take 30 lbs.+ of air, while 3 or 4 lbs. puts
you in the danger zone with others. There all kinds of videos on
You Tube on removing gas tank dents using air.
Might be something there you can use. If this is the only tank you
have for the motor, just be careful!!!!
Tubs
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.