Quote Originally Posted by Rubberhead* View Post
There's a couple of things - voltage drop is one. Any reasonable gauge wire will still increase the likelyhood that a dying battery can't start the motor. If something goes wrong with radio, depth finder or nav lights, I can still get home.

Something going wrong with the charging system will usually cut a trip short. Something going wrong with the starting system and the trip will usually run way, way longer than planned. I try to keep everything I need in easy to get to places and make connections as perfect as possible and runs as short as possible. I even plan to have to unhook the motor's leads from the boat and connect them directly to a battery to get me started.
You put way more thought into that than I ever would. I've had batteries in the front of a boat before and never thought about it and never had a problem either. It's the piece of mind of a two battery system. One battery goes bad, switch to the next or combined the two. If a 10ft piece of wire gets in the way then I would assume it just was not my day to be on the water.