Sizing a Trolling Motor

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maintenanceguy
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Sizing a Trolling Motor

Post by maintenanceguy »

I have a 17' aluminum jon boat and I'm looking for a bow mount trolling motor. The heaviest my boat will ever be fully loaded is under 1,500 lbs. I'm always on salt marsh creeks. When the tide is rising or falling, there is a decent flow of water in the creeks.

I've found several sites that offer sizing charts based on boat length or on boat weight. Different rules of thumb are giving different answers but I seem to be in the range of 40 and 55 lbs thrust. A significant price jump happens once you get over 55 lbs so I would like to stay at 55 lbs if possible but I don't want a trolling motor that won't be big enough for my boat.

So, my question for the trolling motor experts here is: What size trolling motor do I really need? Will a 55lb thrust motor suit my needs?

Thanks for any help.

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Scott F
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Sizing a Trolling Motor

Post by Scott F »

If you will be dealing with current, I’d go with an 80 lb thrust, 24 volt unit. On flat water, a 55 lb thrust unit will move the boat. I had a 55 for years and it was alright, but I’m so glad I upgraded to the 80. I had times with the 55 when the wind was blowing and I had to start the big engine because I was being blown onto shore and didn’t have enough power with the trolling motor.

hipster dufus
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Sizing a Trolling Motor

Post by hipster dufus »

I have a 55# mk on a 1756 cc g3. I absolutely hate it. Speeds 1-3 are useless . If u go with a 70 or larger tm u will only buy it once. I cannot express how much I hate this motor, 500$ mistake. U never regret paying too much for a good product. 70# variable speed is my recommendation. If u catch a sale go to 80#. Did I tell u I hate my 55# mk

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jethro
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Sizing a Trolling Motor

Post by jethro »

I agree, buy as big as you possibly can afford and fit batteries for. The 24 and 36v motors dramatically increase your runtime, so consider that. If an average day is 10-14 hours of fishing, like mine often are, you may want a 24v system. And you say you fish the salt so that means you see wind. I would look for bigger than a 55lb motor personally, but only you can decide how important it is to you. If you pick and choose your fishing days you can go without wind and maybe a 55lb motor would work for you. I work full time, so when I plan a fishing trip I'm there no matter happens with the weather. When I can afford it I'll be installing a 112lb 36v Ulterra with I-pilot and Link. I can't wait!
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BigTerp
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Sizing a Trolling Motor

Post by BigTerp »

jethro wrote:
26 Jul 2019, 08:54
buy as big as you possibly can afford and fit batteries for.
This!! Especially if you're dealing with current.
BigTerp's Tracker Sportsman 16' build-------> viewtopic.php?f=21&t=26774

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jojo
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Sizing a Trolling Motor

Post by jojo »

I have a 45# Minn Kota on my 1648 and it's worthless in current.
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hipster dufus
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Sizing a Trolling Motor

Post by hipster dufus »

Did I tell u I hate my 55# mk edge? Hate it . Give me 250$ and u can have it w a grp 31 battery and a tray. HATE IT

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onthewater102
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Sizing a Trolling Motor

Post by onthewater102 »

The edge came with a trash prop so they could make another $20 sale on the upgrade they offer - unfortunately the weedless wedge one does help it a lot and spending the extra $20 is basically a necessity. The foot pedal needs to be in a recessed tray or it KILLS your knees if you stand on the deck all day.

As for the OP you've got current on any given day, if you have wind working the same direction as the current you'll be fighting twice as much force - I'd say a 55# isn't going to be up to that without being on high the whole time. If cost is an issue the parts for the MK motors are so readily available and they've changed so little over time you can save some major $$$ up front and buy a used one and schedule a rebuild during your off-season. The brushes, seals and bearings you'd want to replace only cost about $25-$30 all in, labor is free if you do it yourself, shouldn't take a shop longer than 1hr to do if you have to pay to have it done.

You can always extend the life of a 12v should you go that route by using 2 batteries in parallel, the 24v's use them in series, net net the 2 batteries are what end up giving you extra run time.
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JohnK
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Sizing a Trolling Motor

Post by JohnK »

I've got a 17ft. aluminum with a 55 maxxum and it's ok for what my fishing style, no current, but if I had to buy a new one it'd be a 24v 80lb thrust just for the heck of it. Crud, I'd buy one now if I could figure out moving the batteries up front. I'm dubious the 55 would move me around sufficiently for 4 hours in any type current.

johnbt
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Sizing a Trolling Motor

Post by johnbt »

I have a Grizzly 1648 that’s loaded down and a Maxxum 70 does a good job moving it. If I don’t have the 9.9 Merc on it I have an old 12v Minn Kota 35 on the transom for a little extra push. And for backing up and loading.

I screwed two cheap battery boxes to the floor and used aluminum scrap to shim the low corners. The wire runs in plastic from the right to the left and then to the bow. They’ve been like that since 2014.

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MrGiggles
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Sizing a Trolling Motor

Post by MrGiggles »

I have a Terrova 80 on a 17' Deep V. Wouldn't want any less now that I've spent some time with it. Will run all day on a charge, and there are no worries of being able to hold the boat in any wind.

DarrellS
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Sizing a Trolling Motor

Post by DarrellS »

I went from a 55 lb to a 80 lb on my 1200 lb 16 ft aluminum semi V and I couldn't be happier . I had to go with group 24's because of space but they last me 6 hrs with no troubles in this 20 mph " breeze " in Texas .

coosa
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Sizing a Trolling Motor

Post by coosa »

I've had my 1652 G3 for a couple of months now and the 45 lb thrust MK is the worst thing about it. I fish in current a lot, and I've frequently had to crank the outboard to get through the shallow places; the TM just isn't strong enough to get it through. I have to run the TM on the highest setting all the time; lower speeds barely move it.

Buying a 24 volt TM is an expense I wasn't planning, but even worse is that there is room for only 2 batteries. Right now it has a Group 29 for the TM and a Group 24 for everything else. I could replace the 24 with another 29 and wire them in series for the TM, crank the outboard with one, and run the other accessories on the other. That should pull them down somewhat equally.

The thing that concerns me is that it doesn't seem like anyone else is setting up a boat this way. The obvious downside is that I could run both batteries down and not be able to crank the outboard, but it's very unlikely that I will do that unless I have a bad battery.

Is there some other issue that I am missing? I would have thought this would be a common way to set up a smaller boat, but it doesn't seem to be that way.

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BigTerp
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Sizing a Trolling Motor

Post by BigTerp »

I have 2 group 27 deep cycles (WalMart Everstarts) setup just like you are describing. I run a 24V 74# MK Maxxum with the 2 batteries in series and then pull 12V off each battery for other accessories and to crank my outboard. Have only ever had issues once where the battery wouldn't crank the outboard, but that was due to a bad battery, not the TM running it dead. I use my trolling motor 90% of the time while fishing for 6+ hours (a typically day for me) to hold me in current and have yet to run the batteries down enough that it wouldn't crank my outboard. I do keep a portable jump starter on board just in case. Makes it worry free to run my TM as I need throughout the day.
BigTerp's Tracker Sportsman 16' build-------> viewtopic.php?f=21&t=26774

coosa
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Sizing a Trolling Motor

Post by coosa »

Thanks BigTerp, glad to hear that others are doing this, and carrying the jump start is a great idea.

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