Before you get to work on boats for the first time, you really need to do some research
on the difference between marine
and structure requirements, and make sure you understand not only what the differences are, but why. For instance tinned stranded wire may not be necessary for home construction, but for marine installation
it really is all that should be used. Same for electrical
fittings, they all need to be cold weld crimped, wire nuts won't last a day.
But as FST mentioned there is a long history
of shoddy work, and a serious lack of professionalism in the marine trade
. Solve those two problems and the knowledge will come.