My pal has a 14' smokercraft and a MinnKotta 55lb thrust RipTide. We troll 4 fat guys without any trouble at a good pace. Get a Rip Tide, or some other salt water trolling motor. That way you can use it anywhere. Try using a standard trolling motor in the salt and it will be ruined in no time! About the same cost, how can you go wrong?
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Organized people are just too lazy to look for things.