I ran a seperate, heavy line from the battery switch, to a junction block, which feeds each device, downriggers, sounder, pumps etc. These are fused individually. Each ground from these devices then go to a junction block seperately. The only things on the switch, are what is reguired to run the motor. I shut off the main switch, when I`m not going to be fishing for extended periods. This prevents any drain on the batteries. I don`t have to worry about the bilge pump, beacuse I trailer the boat, and only have a manual pump switch.