Re: Thrust Question...How many pounds should i need/get..?
There is a formula I used that I found on Cabelas. I just bought a Minn Kota Powerdrive V2 70lb. thrust motor for my '95 Skeeter 200SL Fish n' Ski. It's a 20 ft. boat.
Here is the formula .....
Approximate Dry Weight of boat and engine (you can get an approx. weight for these at this site .....
NADA Boat Values
Then add in your max capacity for cargo and persons. It will be on your capacity plate.
Divide that by 200.
Then multiply that by 5.
The concept is that you need 5 lbs. of thrust for every 200 lbs. of weight.
The formula again is
Actual weight + Capacity weight / 200 X 5 = Pounds of thrust needed.
I wouldn't go with anything less than what you get as a result, because that will only strain your motor and leave you desiring more power.
While the above post is true, a lot depends on where you will be using it. I've run an older Minn Kota 36lb thrust bow mount for years on a 17' fiberglass boat, it's fine for trolling and fishing the banks, but it's not my main source of propulsion. My old Grumman 15' bass boat had an old Mercury Thruster, which I think was only about 18lb thrust or so, it did fine too, but again, it was just for trolling and bass fishing, not cruising.
If your goal is a sole mode of propulsion, then you will need a lot more thrust, but I am also not a fan of huge trolling motors on small boats, while they mov the boat real well, they also draw a lot more current, thus limiting the running time, or requiring that you carry more batteries.
I had a small jon boat and was using an old MK 65, (28lb thrust), motor for years, that motor would let me fish all weekend and then some on a single group 27 battery, when that motor failed, I upgraded to a new 55lb thrust motor, that motor would only run a few hours on a single battery, so I added a second battery in parallel, it barely doubled my run time, partly since I had added another 60 or so lbs of battery to the boat. I gave up on that motor and went out and bought a smaller motor, that motor is only a 22lb thrust MK, which runs all weekend or more as did the old motor. The real kicker is that I don't think I gained or lost any real speed, at least not that you could tell.
The larger 55lb thrust motor did do a lot better in strong current, but would almost kill the battery doing so.
Since then I've learned to go with just enough trolling motor, and not overkill, especially on lighter boats.
