If the decal on you motor is original, to determine the
finish on the tank when new, remove a small section
with some paint stripper. The second example is a 1937
Johnson LS. It would seem to indicate that the Johnson’s
had polished tanks at this time. That may have changed
by 1940. I suspect it was polished. If your motor still has
its original decal, this test will answer your question.
Tubs
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.