RE: soldering connections in a marine environment...
True, it's not for the average "I just bought this iron at Radio Shack for $4.95 handyperson or mechanic" HOWEVER... soldered connections fail under vibration when unsupported, i.e. at the transition from the soldered to the unsoldered wire. Using the proper heat shrink tubing and not applying excessive heat (which encourages the solder to wick up well into the wire and beyond the support of the heat shrink will result in long life connection(s)... also using crimp-on terminlas that do not have an "insulation support" (which usually requires a seperate crimp action unless one has the expensive professional tool) can also result in failure of the connection as well as failing to crimp the "insulation support" (the usual case). I had more than one wire at a crimp-on connection on a used boat I once purchased that had failed at the terminal (improperly crimped insulation support). That was the same boat that I did a solder splice with heat shrink tubing in 1979 that was still sound when I sold that boat in 1995. Normally I avoid splices at all costs unless one has the problem of no clearance for connectors in a cable run as mentioned.

Connections get soldered all the time in military electronics, even for the US Navy and they don't fail... at least not just because they were soldered. It's a matter of technique and workmanship.