On my Tartan 30 several wires, including those from the engine panel and the 8GA positive wire to the main switch panel, run for an extra 20ft for no reason I can determine.
The wires run aft from the panel (just port of the companionway) down a raceway under the cockpit seat and all the way back to the port lazarette. Once in the lazarette, they make a U-turn and run down another raceway next to the port quarterberth and forward under the port berth, into the head. Once the wires exit this raceway they make another pair of turns under the sink and back into the engine compartment.
As far as I can tell, about 20ft of this could be cut out by just going straight from the main panel over the quarterberth down to the settee and then straight to the engine and battery compartments. This skips the run to the lazarette for all the wires (excluding the stern light pos and the rear bus neg) and through the head (excluding the engine panel wires).
My boat layout matches this diagram
on the port side.
(from S&S blog
Can anyone here either explain why Tartan didn't use the shorter run or why I shouldn't?
I'm going to be replacing quite a bit of wiring and cutting out those 20ft would make me feel a lot better about the 8GA main positive wire and let me avoid snaking wire down these really long raceways.