Should I put some auto reset fuses in my tug?
I had another tug about 30 yrs ago that broke down in the middle of central park NYC. I had to wait hrs for it to drift back to shore so to speak!

Maplins call them Auto-reset circuit breaker, 1 - 10A sizes. Solder tags. I have seen them on eBay. To be honest I only use them when testing new models. Only have one in my latest model, nothing in any of the others, yet!

Yes my boat has one speed controller it a Viper Marine 15 with that said I like to say
Thank you for your quick reply and suggestions I'm going to be getting some auto reset fuses.
one can never tell what under the water surface!
Thanks again,

Maplins do some auto reset fuses upto 10 amp. That way if it's just a temp (overload etc). it will reset to get the model back in.

To be really safe you need to fuse each battery positive lead as you are connecting them in parallel so any problem with one battery will affect the other.
You can use the same value fuse for each battery as suggested by Haverlock.
Dave

Thanks, for the response I was a little confused!
I now know what to do.
👍

I guess you have a speed controller!
You need a fuse rated to blow before the speed controller does.

Your fuse ( if you fit one) needs to go in the positive lead to the speed controller between the point where the two batteries are joined and your speed controller.

As to its rating have a look at the Amperage your speed controller is rated at and fit the nearest value you can find to that figure.