Trolling Motor Wiring

[dave potts]

I want to rig my 14 foot jonboat with the battery in the back of the boat for use with the electric start outboard motor and then run a wire up to the front of the boat to hookup the 35 lb. thrust trolling motor and the depth finder. My question is what guage wire should I use?

Most bass boats use 6 guage wiring for use with their larger trolling motors but I kind of doubt I need to go that heavy on this setup. Would 12 or 14 guage be sufficient? I imagine someone on the board has done this and can share their experience.

Thanks,

Dave

[LarrySTL]

I want to rig my 14 foot jonboat with the battery in the back of the boat for use with the electric start outboard motor and then run a wire up to the front of the boat to hookup the 35 lb. thrust trolling motor and the depth finder. My question is what guage wire should I use?

Most bass boats use 6 guage wiring for use with their larger trolling motors but I kind of doubt I need to go that heavy on this setup. Would 12 or 14 guage be sufficient? I imagine someone on the board has done this and can share their experience.

Thanks,

Dave

I'm sure you'll hear from folks with much better credentials than I, including some real marine mechanics here, but I wouldnt do it.

I think a 35 lb TM can pull over 20 amps and 12 gauge wont do that. If you fuse ( or circuit breaker) the 12 gauge at a low enough amperage to make sure you dont fry it, you wont be putting getting enough power to your TM to run it properly, that if you are running a locator and a TM on the same wire, you may lose the reading on your locator every time the TM is on or blow the internal fuse in the locator every time you hit the TM, and that by doing all this plus the electric start outboard on one battery, if your TM runs the battery down too low, you could find that you can't start your outboard.

I'd get two batteries, one for the electric start outboard and the locator, and the other just for the TM. I'd put the starting battery somewhere in the back, run 6 gauge from it to the outboard, and then run 16 or 18 g ( memory fades) from the cranking battery to the locator, with a 3 amp fuse close to the battery. 3 amp will run an older locator just fine, the newer mapping ones may pull more amps, I'm not sure. I ran older locators including graphs wired that way for years without problems.

Then I'd put the troller battery however far forward I needed for weight distribution, and run just the TM on it with 6 gauge. The extra cost this way would be the second battery and maybe $30 more for heavier wiring. If you were willing to risk the dead battery when you wanted to start the outboard, you could run all three off one battery, with three sets of wiring and see if you could get by without battery #2.

If any of the mechanics chime in, please go by their recommendations, not mine.

[David Unnerstall]

You could just match the size of the wire that is connected to the trolling motor from the factory.

[Seth]

I want to rig my 14 foot jonboat with the battery in the back of the boat for use with the electric start outboard motor and then run a wire up to the front of the boat to hookup the 35 lb. thrust trolling motor and the depth finder. My question is what guage wire should I use?

Most bass boats use 6 guage wiring for use with their larger trolling motors but I kind of doubt I need to go that heavy on this setup. Would 12 or 14 guage be sufficient? I imagine someone on the board has done this and can share their experience.

Thanks,

Dave

I would use 10 gauge at a minimum but preferably 8. I have a 12v 55# and wish I had 6 awg but it came with 8 awg from the factory so that's what I have stuck with.

[Bill Cooper]

Dave, 10 gauge wire would be fine for the distance you are running. Install a 30 Amp circuit breaker or fuse. Make sure you use a large enough battery or you will drain it too fast and will not be able to start your engine. If you have a pull starter on the engine, no problem. Another thing to consider, the alternator on your engine will not recharge the battery fast enough to replace what the depth finder and T/M will be taking out. Most small outboards have around a 3-6 amp charging system and some none at all. In simple terms, let's say you operate your trolling motor and depth finder for an hour, conservatively, you draw a 15 Amp load for that hour. If your outboard has a 5 Amp charging system, you will have to run the engine at full throttle for 3 hours to replace the energy used by the T/M & D/F. When looking at batteries pay close attention to the reserve capacity. This gives you an amount of time in minutes at a specific load (generally 25 Amps) before the battery voltage gets too low to start the motor. The higher the reserve capacity, the longer you can troll and still be able to start your outboard.