Trolling Motor size question

[Clint KY]

I have an ?85 Monark 16? Bass Type boat that I am rebuilding. It has an Evinrude Foot Controlled Trolling Motor on it and the manual says it is ?15 lbs of static thrust?. I got it running and just listening to it I compared it to the sound of my 50# Minn Kota transom mount and it seems somewhat puny. I would like a newer TM. Here is the quandary: There a few used 40# TMs around, but I wonder if they are big enough for my boat. I had the 50# on the back of my 16? jon and it was not too big, so I am curious if I should bite the bullet and buy a 55# motor, which are harder to find and of course, more expensive.

 

[Scott Danforth]

Dad's old bass tracker came with a 36# thrust trolling motor and it took him 3 miles against the current when he hit a rock and sheared the lower unit off. if its good enough for a 17' bass boat, a 40# thrust will be just fine for your 16# bass boat.

 

[bassman284]

Clint, the answer is, "it depends". First as to static thrust, I did some reading and that seems to be the standard by which trolling motors are rated. So any 40# you might use will outperform the 15# and may prove to be totally satisfactory to you. The difference between 40# and 50# may not be as big as you expect. I went from 47# to 55# and still feel I get less performance from the 55 so who knows.

I can't figure out if you've tried the boat on the water with the 15# I think you should try that (if practical) see how it does. Maybe you'll find you can live with that for awhile. If it's not enough, like Scott says a 40# might do enough. A lot of it depends on what you expect the trolling motor to do for you.

 

[gm280]

Trolling motor sizes always puzzled me. I read how some want the largest, most powerful trolling motors man has ever made. And I would seriously wonder, what are they doing with such trolling motors. If you are merely trolling down banks and fishing, then you don't need a very large trolling motor to accomplish that. However, if you troll in large open water with serious wind blowing, then go large, even 24 volt or 36 volt. But unless that is the type trolling you do, then a smaller size with not only suffice, but the battery(s) will last longer as well. I can say from pass experience that a Motor Guide III foot controlled trolling motor would move my old Bass boat without any issues. And I think that was a mere 15lb trolling motor as well. So figure out what YOU do with your trolling motor and go from there. Bigger is not always the better choice. JMHO!

 

[Clint KY]

Thanks all. I have NOT tried the boat in the water, as I have a long way to go before it gets wet. Part of the challenge is that I am rebuilding the floors and if I am going to go bigger I have to add some larger wires than are presently being used (12GA) before I install the floor of the boat. There is precious little room to run any more and or larger wires from the rear hatch area (where the batteries live) to the front where the TM is installed. I have run one set of 14GA in the space left by the ribs, as I plan to run a separate AGM battery for the electronics. My logistics background tells me to install the wires in any event, in case I ever want to change the motor to one with which I can troll. I am considering running a length of 3/4" conduit along the junction of the sidewall and the floor to accommodate the 4GA wires that will handle anything I ever want to put up front. Once I get the floor painted, installed and the console put back in I do not want to pull it out again.

 

[fishrdan]

The big question is, what are you going to use the TM for, positioning, trolling, fighting wind/waves or just puttering around on calm lakes? Also, how big is your boat, light outboard aluminum hull or heavy I/O fiberglass hull, big difference. I'm guessing your Monarch is a light aluminum with an OB, and that a 50-55# TM would work fine...

My old heavy 16' fiberglass boat (2800#+) had a 40# transom mount on it, and it worked OK for trolling, it also got me back to the marina a couple of times when the main engine puked. I added a 24V 70# bow mount which was sufficient for casting, but I wasn't thrilled with the foot controlled motor. My current 18' boat has a 70# Power Drive bow mount which I like a lot, works well for both positioning and trolling with a hand-held remote control, but it's an expensive TM...

Regardless or what size of TM you buy, get a "digital" trolling motor as they will go far longer at slower speeds than an old speed coil TM's. I've owned MK and MG, and like MK much better. If you're handy, fixing a used broken TM can get you into a high dollar TM cheap. Both of the MK 70# digital TM's (Vector and PowerDrive) on my 18'er were broken and bought for around $100, and even after repairing them, they were about 1/3 the cost of a new TM.

When buying wire, check out Genuine Dealz. They sell high grade marine wire inexpensively. They also have; tinned connectors, heat shrink tube and misc items you'll need to complete the wiring project properly.

 

[Clint KY]

I am close to answering my own question with a bit of overkill. One of the local crappie crowd just went to electronic steering and has offered me his 107# MG trolling motor at a price I can not pass up. It will be a challenge as the motor is a 36V, but I can make it work, as I have room to mount the batteries up front keeping the wires short. I will be able to troll all day long on a charge and will even feel confident enough to take the boat on the rivers. Twice last year I was stuck on the river (neither time in my boat), once with a dead motor and a 40# TM on a 19' skiff and the other with no fuel and a 70# TM on a 19' aluminum open boat. Rescued the first time by a couple of guys fishing for catfish, and the second by a worker on the shore with about a gallon of gas. I get to see the motor Saturday and will have $ in hand. I will report back.

 

[fishrdan]

107# will move that boat without issue, that's for sure! Better to have too much than too little. Just be careful with the TM on full power as it will yank the bow around.

 

[gm280]

WOW 107lb thrust trolling motor. I hope you have some really BIG batteries because that will eat them very fast. :facepalm:

 

[fishrdan]

WOW 107lb thrust trolling motor. I hope you have some really BIG batteries because that will eat them very fast. :facepalm:

If it's a speed coil TM it will definitely be a battery killer, but I doubt a 107# is speed coil and most likely a digital TM which will sip the power.

I'm running a 70# digital TM on my 14' jon boat (which is overkill), but it still has equal or more run time than the 55 digital TM it replaced and far more run time than the 40# speed coil I used years ago. I use this same 70# TM on my heavy 18'er and can only troll 4 hours before the batteries are depleted, on my light 14'er I can troll 8-10 hours.

 

[NYBo]

107# MG trolling motor

Bonus: electric-powered water skiing!

 

[gm280]

Bonus: electric-powered water skiing!

Well with a 107lb trolling motor, I believe he can get his boat to plane out as well. :facepalm:

 

[Clint KY]

107# will move that boat without issue, that's for sure! Better to have too much than too little. Just be careful with the TM on full power as it will yank the bow around.

That is the same thing a friend here warned me about.

WOW 107lb thrust trolling motor. I hope you have some really BIG batteries because that will eat them very fast.

I will be running 3 batteries - two Size 24s and one size 27. I already have the 27 and will have to purchase the other two. However you are incorrect on "eat them very fast". With the small load I will be putting on the TM, the batteries should last all day, even trolling. (see Dan's comment below.)

If it's a speed coil TM it will definitely be a battery killer, but I doubt a 107# is speed coil and most likely a digital TM which will sip the power.

I'm running a 70# digital TM on my 14' jon boat (which is overkill), but it still has equal or more run time than the 55 digital TM it replaced and far more run time than the 40# speed coil I used years ago. I use this same 70# TM on my heavy 18'er and can only troll 4 hours before the batteries are depleted, on my light 14'er I can troll 8-10 hours.

Yes it is a digital speed control motor. I opted for the big motor for just the reason you state. I am still holding my breath waiting for the actual exchange to happen. I was planning on mounting the TM battery up front as there is precious little space to run any wires from the rear hatch area to the front where the TM lives. Since I am redoing all the decking it will be an easy (yah - right) task to build a battery box just forward of the live-well and storage area under the front deck.

 

[gm280]

Clint, if you are presently replacing the floor and such, why not install some simple and cheap PVC pipe to handle the wire(s) for everything from the back of the boat to the front. Then if in the future you ever need to remove or install new wires, it will be a snap. This is exactly what I did in my refurbish project. You can click on the link below and see. JMHO!

 

[Clint KY]

Clint, if you are presently replacing the floor and such, why not install some simple and cheap PVC pipe to handle the wire(s) for everything from the back of the boat to the front. Then if in the future you ever need to remove or install new wires, it will be a snap. This is exactly what I did in my refurbish project.

I had originally planned to do just that. I was going to run a 1" piece of PVC Conduit along the juncture of the floor and the hull. I got the idea of mounting the battery up front when I started pricing 2 conductor 6 and 8 gauge wire by the foot. At the time I was planning on a 55# 12V motor and only need one battery. When the 36V motor became available I considered the options and decided the boat could handle the weight of all three batteries up front and it would cut WAY down on the cable cost.

 

[fishrdan]

Good idea on putting the batteries in a locker up front, wished I had done that... The batteries will take more of a beating, but it will provide better weight distribution and shorter wiring.

Since you have one group 27 batt already, you may want to opt for the other 2 being group 27. This is one thing that I wouldn't consider overkill as it will give you greater run time and keep the batteries from getting deeply discharged vs the 24's, thus getting more life out of the batteries.

 

[Clint KY]

Good idea on putting the batteries in a locker up front, wished I had done that... The batteries will take more of a beating, but it will provide better weight distribution and shorter wiring.

Since you have one group 27 batt already, you may want to opt for the other 2 being group 27. This is one thing that I wouldn't consider overkill as it will give you greater run time and keep the batteries from getting deeply discharged vs the 24's, thus getting more life out of the batteries.

The shorter wiring was what drove the decision and as far taking less of a beating I will not normally go out in weather that will beat the batteries (or me) up.

The choice of the 24s is economic. I will have all 24s when I can see my way to do so. Since it is looking like this boat will not be ready till spring, I may be able to have matching batteries, both size and age when I get it on the water.