Re: what fuses for which items....
bobbo268: I feel your pain. Am currently repairing / correcting / upgrading the circuits in my boat. The wire size, fuse type and amperage rating, and voltage drop things can be confusing. Here are a couple thoughts that might help.
Blue Sea has an easy to use circuit wizard on its site to help determine wire size. If you input your situation's data (12 VDC, 15' circuit, and 10 AMPs) the calculator advises size 12 AWG is appropriate to keep voltage drop < 3%, though there is nothing "wrong" about using size 14 AWG. It is just a matter of the % voltage drop you are willing to accept.
Secondly, a fuse or breaker does not necessarily open a circuit exactly when the amperage is reached. A 10 AMP fuse might not open until 11.5 to 12 AMPs. Unfortunately it can be the devil's own work to determine the amperage "cushion" a specific fuse might permit. The general rule I am following to size fuses is to add a 15% amperage "cushion" and then round up to the next commonly available fuse size PROVIDED (and this is really important) the manufacturer of the load device does not recommend a lesser AMP fuse, which is common for things like trolling motors, fish finders, etc., AND PROVIDED the fuse size is < the wire's AMP rating. For your situation I second the 15 AMP fuse suggestion.
Cannot help with the switch thing. Switches are one of the things that are, thankfully, OK on my boat - so far.
