After a bit of research and also some trial and error I discovered, soldering is a bad way to make electrical connections on a boat.
Crimping them is best and hopefully with some heat shrink around then after. For wire to wire connections, use heat-shrink that has solder inside and is sealed… i.e. when you heat it up it solders, shrinks and seals, watertight the joint. These things are just simply awesome.
A really good set of crimpers is also worth the investment. The difference between a good name brand and the cheapies I bought originally…. wasted money.
P.S. for making my battery connection et al, I bought a cheap hydraulic crimper. probably will never use it again so life was not important, whereas for everyday connections. I have a great US made brand which has proved worth the little extra. Oh and who’d have thought a battery powered heat gun would make sense… trust me it does.. never run out of juice on a project yet and it just works!!!!!