I'm swapping out trolling motors - from a 12volt 44lb Motorguide to a 12/24 volt 65lb MinnKota. The boat currently has 8 gauge wiring and 40 amp breaker. Do I need to rewire with 6 gauge and put a larger breaker in?

for that size your fine with the wiring that you have, 40 should be good but check what is recommended and use that.

6 ga is always better than 8 ga. I would use a 50 amp. circuit breaker.

Thanks Tommy. I was actually going to give you a call this morning and ask you.

with 24v you will better of than before (12v)because the amperage draw will be lower.

I'm assuming that the jumper cable between the batteries needs to be the same gauge as the cable from the batteries to the TM?

Still better to use 6 AWG.

Go with the 6ga and a 50A breaker. The trolling motor is going to draw between 40 and 45A.

look at the amp draw on the motor see what name plate rating says if 40 amps or less you are wasting your money to change because the higher the voltage the lower the amp draw

What he said! You can never have too big of a wire but too small and you will have problems.

I went with the 6 gauge. Got the trolling motor hooked up and the stupid thing runs backwards (its pulling the boat instead of pushing). Double-checked the wiring and everything is wired correctly. Will be giving Boris a call real soon.

If it's mounted on the front....it is pulling the boat!!!!!!!
If it is on the rear it is pushing the boat!!!!!!!