Something interesting when you run wires in a plastic kayak..
This diagram shows a fuse close to the battery. On my setup, that fuse is less than 5 inches from the battery.
I put the battery pack up near the front of the boat because the two round access hatches in front of each seat are used for storing stuff like water, cell phone, camera, lunch.. etc. I could have put the battery in the round hatch all the way to the rear.. but I wanted the weight up front since I solo from the rear seat.
Point being that I have a DC wire run from that battery box through the hull and to where the chart plotter is located. In the future, this wire run may power other things also..
These are small batteries but I am guessing that if you shorted the battery terminals, whatever was shorting the battery terminals would get very hot. If this is a set of 14 gauge wires running through the hull with the battery on one end and a short on the other end.. I hope to never find out what would really happen but at the minimum, I can imaging some plastic getting melted.
So the purpose of that fuse very close to the battery is to protect the wire from melting something or starting a fire in case of a short anywhere along the wire run. The closer that fuse is to the battery, the less wire that is not protected.
Note that I have a 3 amp fuse in there but since 14 gauge wire is rated for about 20 amps, this fuse could be as high as 20 amps and protect the wire from a short.