Thanks Len1, much appreciated!

I got a chance to take a few pictures showing the disconnect I mentioned. It is mounted to the top of my battery with velcro. If you push the red button the circuit breaker will open and disconnect the feed. I use this button when I want to put the boat to "sleep". To reset the breaker from the open/sleep mode just push the lever sideways. You also push the lever sideways to reset the breaker after there is an electrical overload causing the breaker to trip.

Fuses, or circuit breakers(preferrably the auto-reset type) are very inexpensive insurance. I worry, not so much about fire, about picking up weed or fishing line, enough to potentially overload my ESC even though I try to plan on my ESC's being 150% overcapacity.
I look at fuses like my generator at my house. While the cost is wrapped up in the generator that I almost never use, when I need it, it is there.

I protect the entire electrical system on my 42"tug with a STETION Car Audio 40 Amp Resettable Fuse Circuit Breaker Car Protect for Audio System Fuse 12-24V DC for Car Audio Amps Overload Protection which I bought from Amazon.
What is nice about this device is that you can disconnect the entire electrical system with just the push of the on board button and it acts as a resettable circuit breaker in case there is an overload condition. I have it installed between my battery the main distribution panel. At the end of the day or when I take the boat out of the water all I have to do is push the button and the electrical system is disconnected.
In addition I have fuses protecting individual branch circuits. LEN1

In all years that I've been model boating and with a variety of boats I had a"fire" issue only once. That was because the ESC that I was using was way too low in the current rating. (No serious damage. )

Of all the model boats that I have only one boat has fuses that I put in it. I don't install fuses anymore.

Every every ready to run model boat that I have seen does not have fuses.

Lew

If your motor and ESC setup BL10A in runner from Prestwich models I suggest you ask them as they say this motor is suitable for a Perkassa so I assume they also advise a prop which will ultimately set the running current. My Sea Queen is a similar size and uses a 42xx outrunner motor with a 35mm 3 blade brass prop and runs on 27 amps with 11.1v at full speed. Slow speed uses about 10 amps. Any weed and the current will increase dramatically.
dave976

I appear to have overlooked the fitting of a fuse in the fit out of the Perkasa. I do have a large on-off switch, but currently no fuse.

Have to admit to getting confused reading around the subject, a lot of fast electric boats don't bother with a fuse but I'd feel happier with one installed

I'll be running a Brushless 4083 1100kv motor and 150 Amp ESC controller with a 5000Mah 3S LiPo. All cables are 10AWG

I'm assuming the motor/ESC wont usually be drawing 150 Amp, what would be a realistic size fuse to install? I'm assuming I'll have to use a heavy duty strip fuse.