and thank you for your welcome. It’s an interesting forum and there is a lot to discover…
(I only beg to excuse my mistakes when posting – I’m not a native English speaker)
among submarine modellers here in Germany this theme was discussed also and some collegues just mentioned the same argument – they worried about a blown fuse when the model was submerged.
But honestly spoken – what would be the benefit if fuses were omitted?
A fuse with a rating matched to the cable size and worst case operational current won’t blow without serious reason. If it blows you will have a severe fault situation where more damage would occur if the fuse was omitted. May be the cables would melt and act like a fuse by themselves. Even worse scenarios could happen, you don’t need much fantasy to imagine. And it is not sure that your sub is able to resurface when you have a short situation on board (causing a large voltage drop across your battery).
It seems more useful to build up a power distribution with a main battery fuse (slow blow, ratings perhaps 20amps or 30amps, e.g. car fuses) and individual fuses for the different branches of the distribution with lower, bur also matched ratings. So if your propulsion motor would stall and blow his fuse (instead of burning off by himself), the main battery fuse would remain intact and also the branch for the power supply of your diving system. The model could resurface then (otherwise, with burnt cabling probably not).
I must confess that I hadn’t spent much time by thinking about this theme – in former times I had also no fuses onboard. But when the years go by (now I am an old lad of 56 years) and you get more experience and knowledge about things that went wrong I’ve become more careful…