Thrust Chart

[moondok]

Does anyone know of a chart that shows thrust to weight ratio for trolling motors? <br /><br />I want to know how many pounds of thrust is needed to push "x" pounds of boat mass at given speeds.

 

[Realgun]

Re: Thrust Chart

A lot depends on how your pushing the boat. if you going forward with a flat bottom and calm water then 5 lbs will move it forward. but if you reverse it it might take ten due to the flat rear on that boat. Add wind, current, a deep V and things change.<br /><br />Trolling motor were designed to move the boat slowly. Usually less than 5 mph.

 

[moondok]

Re: Thrust Chart

The reason I am wanting such a chart is because I have a pontoon boat. Everyone has a different opinion on how much thrust is needed to push it at different speeds. Because of it's size (21'), I want a trolling motor that can be there for backup if the outboard has problems. I understand that wind has a lot to do with speed, but I can adjust for that if I know how fast the boat will move in "no wind" conditions. <br /><br />A local store has a really good deal on trolling motors right now. $200 for a 50 pound thrust MinnKota (sp?) 12 volt. I'm wondering if 2 of these would get 10mph. This pontoon is roughly 4000 pounds. That is just an estimate from what I've read on the net. If I'm wrong, just tell me.<br /><br />Hope this helps clarify my situation. Pontoons seem to be the exception when it comes to trolling motors. Most people around here would laugh at the idea of putting something so small on such a large boat.

 

[ufm82]

Re: Thrust Chart

There are too many variables for a "chart" so to speak and the companies tend to use a method of thrust measuring that is kind to them. It's tough to decide how much is enough or not. I can't help much with the ratio but I do know that a big motor can be run slow but a little motor can't be run any faster. <br /><br />Pontoons have special needs mainly due to their high deck heights. They'll require a very long shaft and 60" is pretty common. For a 21' boat that weighs what you claim it does, I wouldn't waste time buying two motors- you're gonna have to buy two batteries anyway, so you may as well buy a 24V motor to start with. Get one of the bigger MinnKota pontoon versions- they'll crank out 70+ lbs of thrust and do it well. I can't imagine trying to mess with mounting, wiring and controlling two separate motors, especially if you are depending on them in case of an outboard failure. <br /><br /> Other than the high wind drag a pontoon offers that may require more thrust, there's no other differences other than shaft length and maybe mounting systems. The motors are the same. <br /><br />You could go ultimate and run a MK 101 36V beast with three batteries- I doubt a 21' pontoon would even know that extra weight was there. Got about $1,500 to spend? LOL<br /><br />UFM82

 

[moondok]

Re: Thrust Chart

LOL, I looked at a 164lb thrust on the net recently. It was a measly $1399. So that is a no go.<br /><br />I have one 50lb thrust on it now just for getting back into the tree tops for crappie and brim. While a 34lb thrust won't cut it,(tried it), the 50 does a nice job. The only problem is the lack of speed. Logic tells me that 100lbs of thrust would move the boat faster, but I know that logic in this case fails due to the company making the motor. I had a feeling that 2 or even 3 motors, which would be a royal pain to control, would NOT increase the speed all that much. I guess it would be comparable to adding torque in a car. You get more hauling power but no more speed.<br /><br />Since the area where I fish is small, I even considered removing the outboard to lighten the load a touch.<br /><br />Thanks for the comments though. I want several opinions because this isn't something that has been tested all that much.

 

[BlackKnight755]

Re: Thrust Chart

Moondoc,<br /><br />This may be an answer to what you are looking for. Electric Motor This may or may not be something that you could use.

 

[BlackKnight755]

Re: Thrust Chart

... or something like this maybe Another Electric Motor Just trying to be helpful with as many options as I can find.

 

[Luna Sea]

Re: Thrust Chart

Forget the 164 lb. thrust. But the 36 volt 101 lb'er is about $75 more than the 24 volt version. I had one on my 20 foot lund and it certaintly wasn't overpowered....... <br /><br />Good Luck

 

[moondok]

Re: Thrust Chart

Thanks for the ideas guys. I didn't even know they made the full size dual trolls with electric tilt.