Where to put fuse in boat?

Hook them to the breaker panel and then leave the little fuse holder above the mounting surface.Use a breaker to turn the power on to the unit(s) one for both if necessary .breakers are to mainly prevent the wires from catching on fire if they ground out.

Isn't there an in-line fuse on the wires from the VHF radio and the Fishfinder? They usually have one on them.
Give yourself enough wire to be able to take the device off it's bracket, to access the back of it, without having to disconnect the wires....you'll be glad you did.

An in-line fuse is easy to install, and if you shrink-wrap the connections, it's going to be water-proof too.

Oh, am I on Fishboat.net??:B

Make sure you use marine grade wire, it's worth it.

It's just that the "power panel" is so close to the devices it is only a matter of a foot of wire between putting them behind the screwed on gage panel or outside. I just thought outside closer to the devices would be better for access. :h

A fuse may help protect the device under some conditions but that's not it's purpose really. Protecting the device isn't very practical. For instance, your VHF might pull 2 amps on receive and 6 amps on transmit. So, you need maybe a 7.5 amp fuse. If something goes haywire in receive mode and it pulls 6 amps things will still burn up but the fuse won't blow.
Any wire coming from a battery should have a fuse if it runs very far. The possibility of a short makes this important. If you have a very heavy, short wire going to your fuse panel a main one in the big wire isn't that big a deal.
If it were my boat I'd keep the new accessories matching the existing. I'd install panel mount switches with fuse holders. Then changing them is easy. Even better is to use a panel with resettable circuit breakers.
Put the fuse as close to the panel as practical, if that's outside for access I wouldn't worry about it.