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Choosing
Trolling motor as a bow thruster: will it work on your boat?
Sometimes, and your boat decides which way it goes. How heavy she is and how much of her the wind can get hold of matter most.
- Our sizing beside owner reports
- Light boats and heavy boats
- What a real thruster costs
- A 115 lb motor covers, on paper 6 of 6 › of the boats in our table, from the very bow in 15 knots. Heavy-boat owners say otherwise.
- A 40 ft trawler needs 78 lb › at the very bow in 15 knots, where a trolling motor mounts. It is the longest lever on the boat.
- A tunnel needs, for the same turn 33 to 42% more › than a unit at the very bow, because it sits further back on a shorter lever.
- A no-hole thruster, unit only from $3,950 › A rail-mounted or external unit. Neither needs a haul-out.
- A tunnel installed, 35 ft boat $10,200 to $14,300 › With a haul-out and a hole below the waterline.
- Sold as a docking thruster None › No maker sells or rates a trolling motor as one.
The short answer
Our sizing numbers sit beside what owners report, so you can see which side of the line your boat is on.
- Light boats: often yes On a pontoon, a A pontoon boat with three logs instead of two., a light aluminum boat or some houseboats, owners say a modern auto-deploy trolling motor works for docking. What owners report
- Heavy boats: owners say no On a A hull that pushes through the water rather than climbing on top of it. Most sailboats and the heaviest trawlers have one, and they carry a lot of weight for their length. much over thirty feet, owners say it does nothing at all in the conditions where they wanted a thruster. Where the two views disagree
- The arithmetic is kinder than the owners Our size calculator says a 115 lb trolling motor works on paper for all 6 boats in our table. That includes a 32 foot cruiser, and owners of boats that size and larger say otherwise. What the numbers say
- The forum answer is dated Most threads were written between 2004 and 2013. That was before auto-deploy, wireless remotes and GPS position-holding, and it is why the threads you found disagree. Why it is out of date
- It is still not a thruster Nobody sells a trolling motor as one. If your boat is heavy, look at the no-hole thrusters instead. The thruster finder, our free tool that matches a thruster to your boat, lists the ones that fit yours. If your boat is heavy
What the numbers say a trolling motor can do
You might expect a trolling motor to be far too weak. Our own sizing calculator does not say that.
Minn Kota publishes trolling motors rated at 115 lb of thrust. On paper, that covers a surprising number of boats.
| Boat | Needs at 15 kt | 115 lb? |
|---|---|---|
| 20 ft pontoon | 30 lb | Works on paper steers her at 29 kt |
| 24 ft tritoon | 45 lb | Works on paper steers her at 24 kt |
| 28 ft sailboat | 38 lb | Works on paper steers her at 26 kt |
| 32 ft planing cruiser | 30 lb | Works on paper steers her at 29 kt |
| 36 ft houseboat | 113 lb | Works on paper steers her at 15 kt |
| 40 ft trawler | 78 lb | Works on paper steers her at 18 kt |
What our calculator says each boat needs at the very bow, where a trolling motor mounts, against the 115 lb a top-end one publishes. Each figure is the push that keeps her steering in that breeze.
These are the kindest figures a trolling motor gets. The bow is the longest lever on the boat. A tunnel has to sit back where the hull is deep enough to hold it, and from there it needs about a third more thrust for the same turn.
A 20 ft pontoon reads the same as the 32 ft planing cruiser, and the 24 ft tritoon reads more. That is the wind. A pontoon’s canopy and flat sides catch far more of it for her length than a low cruiser does, so she needs more push at the bow for the same turn.
Every figure in that table is the size calculator's, worked from the wind on the boat's The area of the boat the wind can push on: the hull sides, the cabin, the mast and rigging, or the canopy. A tall, boxy boat has a lot of it, and wind force does not care how slowly you are moving.. Each boat is sized to the same 15 knot design point as every other page on this site, to keep her steering at docking speed.
What owners report
On a 32 foot cruiser the table above says 115 lb works on paper. Owners of boats that size and larger say otherwise. They have said it the same way in threads from 2004 to 2023, on the three forums quoted on this page.
Here is the owner of a 38 ft canal cruiser, writing in 2013.
“I might as well have been trying to push a freight train uphill. It wasn't all that small but it had absolutely no effect on the boat.”
Owner of a 38 ft canal cruiser, iboats, November 2013
Another owner in the same thread put the problem in one line.
“I can't imagine 100 lbs of trolling motor doing you much good in the conditions where you NEED a thruster... IE cross wind and current.”
iboats, November 2013
On lighter boats, owners report the opposite, just as consistently. This is the owner of an 18 ft aluminum boat.
“i have an ulterra on the front and actually use it like a bow thruster for docking in tight quarters. it works really well like that.”
Owner of an 18 ft aluminum boat, The Hull Truth, June 2023
A second owner in that thread agreed.
“Absolutely. Works fine. You can pull it high up and gives you bite still to turn the bow.”
The Hull Truth, June 2023
Where the two views disagree
Our calculator and twenty years of owner experience disagree about boats in the thirty-something-foot range. Both are evidence, and we have not closed the gap.
Thrust is probably not where the disagreement lives. Four other things are likely doing the work. This is our reasoning, and none of it has been measured.
The ratings may not be measured the same way. Trolling motor pounds and thruster Pounds-force: a pound of push, written as a thrust rating. It is the same figure most people write as lb. both describe static pull. We could find no published statement that the two use the same test. Until somebody publishes one, treat a direct 115-against-90 comparison with suspicion.
Direction. A thruster pushes straight sideways, because that is how it is built. A trolling motor pushes wherever it happens to be pointed. Only the sideways part of that push does anything for you, so aim it forty-five degrees off and you lose a good part of your number.
Time. Our calculator answers how much force it takes to steer this bow. Docking asks a harder question: how much force, applied within two seconds, in the right direction, while you are also on the throttle.
Depth and grip. A trolling motor's propeller sits near the surface. There it is easier to suck air and lose bite in chop. A tunnel sits well under.
The practical reading. “Works on paper” means only that the arithmetic finds enough thrust. On a light boat with that reading, a trolling motor is worth trying before you spend five figures. On a heavy boat, or where the margin is thin, believe the owners over the arithmetic.
Why the forum answer is probably out of date
Most of the threads that rank for this question were written between 2004 and 2013. The oldest we found is from June 2004. Every one of them describes a tiller-steered trolling motor. You lowered it by hand, walked forward to it, and aimed it.
Auto-deploy, wireless remotes and GPS position-holding changed that experience on a light boat. Almost every “yes, this works” report we found names one of those features. The heavy-boat answer still stands, because a heavy boat is still a heavy boat. But a 2013 thread is not evidence about a 2026 product.
One owner saw the newer kind put to exactly this use.
“I've seen someone with an auto deploy trolling motor on a houseboat specifically for this purpose.”
The Hull Truth, June 2023
What goes wrong, from owners who tried it
None of this shows up in a product listing.
Deployment time. The moment you need the bow moved is not the moment you want to be lowering something.
It only helps one end. A bow-mounted unit does nothing for a stern that is blowing off the dock. That is the problem a lot of owners are trying to solve.
Mounting and wiring. Deck bolts, a battery to find room for, cable runs and a charger.
It hangs off the front. The mount sticks out past the rubrail, which matters in a tight slip and at a fuel dock.
Bow space. Many A pontoon boat with three logs instead of two. do not have enough of it for a conventional bow mount.
The case for no hardware at all
A good number of the people answering this question on the forums think the premise is wrong. They are not just being difficult. This is the bluntest version, from 2004.
“Trolling motor makes no sense at all... unless you're trolling.”
YachtForums, June 2004
Pontoon owners make the more practical version of the same point. A dock line run forward or aft at an angle rather than straight across. Held against the engine, it pulls one end of the boat in to the dock. It is the cheapest docking aid there is., and the engine worked against them, solve a great many slips for free. A season of deliberate practice is cheaper than any of the hardware on this page.
One Bennington owner simply gets close enough to step off and walk the boat in (the Bennington owners’ club forum, 2017). That works.
It stops working when you are short-handed or the slip is tight. It also stops working when stepping off a moving boat is no longer something you want to do. That is usually when people start reading pages like this one.
What it costs next to a real thruster
Most people arrive here holding a quote. Here is how the routes compare.
| Route | Cost (unit only, or installed where it says so) | Haul-out | Hole below the waterline |
|---|---|---|---|
| Trolling motor, top of the range | Not priced here | No | No |
| Rail-mounted thruster, bow or transom | $3,950 plus track, unit only | No | No |
| Bracket-mounted external | $4,495–$5,495, unit only | No | No |
| Boatyard-installed tunnel, 35 ft boat | $10,200–$14,300, installed | Required | Yes |
US prices, 2026. The installed tunnel figure is the 35 ft row of the by-length table on the cost page.
The trolling motor row is unpriced. Prices vary too much by shaft length, voltage and features for one figure to mean anything.
Compare the whole job. A Sideshift unit runs off the boat’s cranking batteries. Budget $250 to $1,000 for batteries and heavy cable, Sideshift’s own published figure, and about 8 to 20 hours to install it by our estimate. A DockStar needs none of that wiring, because its battery and charger are inside, and DockStar puts installation at 1 to 3 hours.
Our installed estimate counts each Sideshift kit’s own batteries, heavy cable and a charger, at $601 to $2,136.
What this means when you dock
If your boat is light and its row in the table reads “works on paper”, a modern auto-deploy trolling motor is worth trying before you spend five figures.
If your boat is heavy and the dock sees crosswind and current, owners say a trolling motor does nothing useful there. Look at the no-hole thruster options instead.
If it is the stern that blows off the dock, a bow-mounted trolling motor does nothing for it.
If you dock short-handed, remember the moment you need the bow moved is not the moment you want to be lowering and aiming a motor.
If your boat is heavy or your slip is exposed
A trolling motor is not going to fix it, and you should not spend money finding that out. The question then is how to get a real thruster without the A tube bored straight through the hull below the waterline, with a propeller in the middle of it. It is the conventional thruster. Installing one is mostly a labor job rather than a hardware one., the Lifting the boat out of the water on a travel lift or a trailer so work can be done below the waterline. It is billed separately from the job itself. and the five figures.
- Which options avoid a hole below your waterline, taken from the installation manuals. Only two categories do.
- Work out what your boat needs from what kind of boat she is and how long, sized to keep steering in a 15 knot breeze.
- What a tunnel install really costs, and why the labor is roughly half of it.
The nearest thing to a trolling motor that does the job. A deck or The flat surface across the very back of the boat. rail-mounted thruster does what you hoped a trolling motor would. It rides on a track and carries its own battery. You lower it to dock, and it lifts clear of the water on its track when you are underway. It shoves sideways the instant you touch the control.
DockStar publishes 90 lb, no more thrust than a big trolling motor. The difference is that it pushes straight sideways the moment you ask, and it needs no hole and no haul-out.