Sizing an electic trolling motor

[gair]

I have a mercruser 470 19 ft fiberglass boat with a 224 cu. in 170 hp made in 1978 6 passenger.

could I push this with a minn kota engine mount electric. Minn kota has these up to 220 lb thrust.

How do I figure out how much of an electric motor to use? don't want another gas engine on the boat.
gary

 

[reelfishin]

Re: Sizing an electic trolling motor

You may want to contact Minn Kota to see what they think. You will need the weight of your boat and the type of hull. It will also depend on what type of trolling you plan to do. Even a smaller bow mount bass boat style motor will move a larger boat provided it's not super heavy. The type of water also will determine what you need. I have a 36lb thrust bow mount motor on one of my trihulls, it does fine in lakes and slow moving water but most likely wouldn't do much in the river or any current. Its only there to allow me to troll along the lake's edge when fishing.

 

[gair]

Re: Sizing an electic trolling motor

went to the local Minn Kota dealer and they said none of the mountable would work on this type of boat, even though they go up to 75lbs of thrust.

was just going to use it in calm waters, to do like you do, go along the shore in bays on lakes in montana.

went to the minn kota site and left a message using there support feature. No one from there even acknowledges that I asked, let alone answers the question, which is why I hoped someone on this forum would know all about how Minn Kota calculates their thrust figures.

thanks

gair

 

[Silvertip]

Re: Sizing an electic trolling motor

You have more than just the required "thrust" to consider. That thrust comes from batteries and 220# requires lots of them so space also is a major consideration. The next consideration is how far and how fast you need to move the boat. That said, a heavy, 19 footer would probably get by with a 74" bow mount but that would likely be a minimum requirement. That also means the motor requires 24V so two 12V batteries in series is required. As you get into the bigger motors, 36V is required (3 batteries in series). For drive mounted motors I would think 80# (24V) would be adequate for your use. Go to 100# (36V) if you are really pushing a heavy load and having to deal with windy conditions and/or need to move about quickly.

 

[Texasmark]

Re: Sizing an electic trolling motor

Probably the best answer is that you never have enough TM for every occasion. There is always something that taxes to the limit whatever you select.

Even if you say what you said, there will be times when cross winds or currents are driving you onto the rocks or something like that.....maybe you are in distress, the engine won't start. Maybe the engine conked out and it is getting late and you want to make it back to the dock type things.

If there is no wind and no current and you just want to put the boat in motion and aren't in a big hurry to get it moving a 10# would do it. But we all know that you want more than that so as Silver says, get it as big as you have accommodations and you will probably be happy with your selection.

Mark

 

[Silvertip]

Re: Sizing an electic trolling motor

Mark -- I left you a private message!

 

[reelfishin]

Re: Sizing an electic trolling motor

If your looking for an example, I have a bow mount, long shaft, I believe though it's only a 42" length on an 18' trihull. The motor is an older MinnKota Turbo 36 which I believe is under 30lbs of thrust. I occasionally use the boat for bass fishing in a local river, so the trolling motor comes in handy. It is by no means a true second means of propulsion, it is just enough to move the boat along the shallows while fishing, I doubt it would be able to get out an into the current and take me back to the dock if the main engine failed. It came with the boat and does fine for the purpose intended. Battery life is real good with the smaller motor, I can troll all day without any problem or chance of killing the battery. If I needed to navigate in heavy current with a trolling motor, I would opt for a newer higher output trolling motor.