Trolling Motor Size Chart: Thrust, Voltage and Shaft Length

Size a trolling motor by your boat's fully loaded weight, not its length. Minn Kota recommends 30–40 lb of thrust on 12 volts for boats up to 1,599 lb, 40–55 lb (12V) up to 2,599 lb, and a 24V motor with 70 lb or more above that. Then pick the shaft length from how high your mount sits above the water.

This guide is research-based. It pulls together Minn Kota's and Newport's published sizing guidance, Bass Pro's thrust formula and manufacturer specs. We haven't installed or run these motors ourselves.

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Trolling Motor Size Chart (Thrust and Voltage by Boat Weight)

This is Minn Kota's motor selection and boat size guide, the same thrust table Bass Pro's guide uses. "Boat weight" means everything on board: hull, motor(s), batteries, fuel, gear and people.

Loaded boat weight	Typical length	Minimum thrust	Voltage
Up to 1,599 lb	Up to 14 ft	30–40 lb	12V
1,600–2,599 lb	16–17 ft	40–55 lb	12V
2,600–3,599 lb	17–18 ft	70–80 lb	24V
3,600–4,599 lb	18–19 ft	80–90 lb	24V
4,600–5,599 lb	20–23 ft	112–115 lb	36V
5,600–9,999 lb	24–28 ft	112–115 lb	36V
10,000–15,000 lb	28–35 ft	115 lb	36V

Minn Kota adds: "If things like wind or current are major factors where you fish, consider extra thrust." Treat these numbers as minimums.

A quick formula. Bass Pro's trolling motor guide gives a rule of thumb of 5 lb of thrust for every 200 lb of loaded boat weight (2.5 lb per 100 lb). Use it to check a boat that falls between rows, then round up to the next motor size.

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How Much Thrust Do You Need? A Worked Example

Add up the real loaded weight, apply the formula, then compare it with the chart and take the larger number.

Say you have a small aluminum boat:

• Hull: 300 lb (use the dry weight from your boat's capacity plate or spec sheet)
• Two anglers: 400 lb
• Trolling motor battery: 60 lb
• Gear, cooler and anchor: 80 lb
• Total: 840 lb

Bass Pro's formula gives 840 ÷ 200 × 5 = 21 lb of thrust. Minn Kota's chart puts any boat under 1,600 lb at 30–40 lb. So the answer is a 30 lb motor at minimum, and 40–55 lb if you fish wind, current or a boat with a lot of windage. Because the chart's floor is 30 lb, most small-boat owners end up choosing between 30, 40 and 55 lb.

In an iboats thread from a first-time owner sizing a motor for a 16 ft boat on a windy lake, the replies made the same point: size up, because a motor that doesn't have to run flat out all day handles wind better and is easier on the battery.

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Trolling Motor Size by Boat Type

The chart covers boats from 1,600 lb up. Small-boat owners need a bit more interpretation.

Boat	Typical thrust	Voltage	Shaft (transom)	Notes
Kayak	30–55 lb	12V	Set by the kayak's motor mount	Light enough for the smallest motors; see our kayak picks
Canoe	30–40 lb	12V	Measure the mount height	Newport lists 36 lb for 8–12 ft boats
Inflatable boat	30–55 lb	12V	Measure the transom height	Needs a transom bracket rated for the motor
Jon boat, 10–14 ft	30–55 lb	12V	Usually transom; measure	Two anglers plus a battery is usually well under 1,600 lb
Jon boat or small V-hull, 16–17 ft	40–55 lb	12V	Transom or bow; measure	Go 55 lb if you fish wind or current
17–18 ft bass or deep-V boat	70–80 lb	24V	Usually bow; measure	Two 12V batteries in series
Pontoon, 20 ft and up	80–115 lb	24V or 36V	Bow mount, long shaft (see below)	Size by loaded weight, not length

Newport's own selection guide sizes by length instead: 36 lb for 8–12 ft boats, 55 lb for 12–16 ft, and 86 lb for 16 ft and up. Length is a rough shortcut. Two 16-footers can differ by hundreds of pounds, so use weight when you have it.

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What Shaft Length Do You Need?

Measure from the spot where the motor will mount down to the waterline, then read the shaft length off the chart. Minn Kota recommends submerging the center of the motor at least 12 inches, with the propeller tip at least 12 inches below the waterline, so the prop doesn't churn at the surface.

Transom mount (Minn Kota):

Transom to waterline	Shaft length
0–10 in.	30 in.
10–16 in.	36 in.
16–22 in.	42 in.
22–28 in.	55 in.

Bow mount (Minn Kota):

Bow to waterline	Shaft length
0–10 in.	36 in.
16–22 in.	42–45 in.
22–28 in.	48–52 in.
28–34 in.	54–60 in.
34–52 in.	72–87 in.
52–72 in.	100 in.

Minn Kota's bow chart jumps from 10 to 16 inches. If your bow sits in that gap, we'd take the 42-inch shaft: a shaft that's slightly too long can be raised in its bracket, but one that's too short can't reach deeper water.

Measure with the boat loaded. The waterline rises when you add people and batteries, so measure at your normal fishing load.

Pontoons have high decks, so they usually land in the long-shaft rows of the bow chart. Measure from the deck at the mounting spot to the water.

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12V vs 24V vs 36V: Which Voltage?

Use 12V for kayaks, canoes, inflatables and most jon boats; 24V once you need 70 lb of thrust or more; and 36V only for boats past about 4,600 lb loaded, per Minn Kota's chart.

• 12V runs on one battery. Every motor up to 55 lb in the chart above is 12V.
• 24V needs two 12V batteries wired in series. A 24V motor makes more thrust for the current it draws. Newport's specs show the effect: its NV-Series 55 lb motor (12V) draws up to 52 amps, while the 86 lb version (24V) draws up to 48 amps.
• 36V needs three batteries, which only makes sense on larger boats with room and capacity for them.

On a small boat, every extra battery adds weight, cost and space, so don't step up a voltage tier unless your loaded weight needs it.

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How Big a Battery Does Each Motor Size Need?

Divide the battery's amp-hours (Ah) by the motor's amp draw to get runtime. A motor's maximum amp draw is its worst case at full throttle; at lower speeds it runs much longer.

Newport publishes full-throttle runtimes on a 50Ah battery for its motors:

Newport motor	Max draw	Full-throttle runtime on 50Ah
36 lb (12V)	29 A	1.72 hours
55 lb (12V)	52 A	0.96 hours
86 lb (24V)	48 A	1.04 hours

Most anglers spend the day well below full speed, so real runtime is several times longer. Newport recommends a battery of 50Ah or larger for its motors. Lead-acid batteries shouldn't be run flat, so with AGM or flooded batteries plan on using about half the rating. Lithium (LiFePO4) batteries can use most of their rated capacity.

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Example Motors for Each Size

Three motors that line up with the main rows of the chart. Specs come from the manufacturers' pages and were cross-checked on a retailer listing. The ratings are our research scores, not test results.

Use the Amazon buttons for current prices.

30 lb, 12V: Minn Kota Endura C2 30

4.3/5our score

The Endura C2 30 (part number 1352270M) is the standard entry point for the 30–40 lb row. Minn Kota lists 30 lb of thrust, 12V, a 30-inch shaft, 30 amps max draw and a weight of 19 lb, with 5 forward and 3 reverse speeds and a push-to-test battery meter. It's a freshwater, hand-steer transom motor.

A 30-inch shaft matches transoms 0–10 inches above the water, which covers most canoes, kayak motor mounts and small jon boats. At 30 amps max, a 50Ah battery gives about 1.7 hours at full throttle by the Ah ÷ amps rule.

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55 lb, 12V: Newport NV-Series 55 lb

4.4/5our score

The 55 lb NV-Series sits at the top of Minn Kota's 12V range (40–55 lb), which makes it a good fit for 12–16 ft jon boats and inflatables that fish in wind. Newport lists 55 lb of thrust, 12V, a 30-inch shaft and 52 amps max draw, and a motor weight of 23 lb. Newport markets the NV-Series for salt and fresh water and includes an LED battery indicator.

The 30-inch shaft is the one limit: it suits low transoms (0–10 inches to the waterline). If your transom sits higher, Newport's 62 lb version comes with a 36-inch shaft.

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86 lb, 24V: Newport NV-Series 86 lb

4.1/5our score

When the chart moves you into the 24V rows, the 86 lb NV-Series is a transom-mount option. Newport lists 86 lb of thrust, 24V, a 36-inch shaft and 48 amps max draw, and a motor weight of 25 lb. Retailer listings call for two 12V batteries of 50Ah or more wired in series.

That's the trade-off: two batteries instead of one. On a 16 ft-plus boat that's carrying the weight already, it buys you much more thrust per amp. On a light jon boat, the 55 lb 12V motor is usually the better fit.

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Frequently Asked Questions

What size trolling motor do I need for a 14 foot jon boat?

Usually 30–55 lb on 12V. A 14 ft jon boat with two anglers and a battery is typically well under 1,600 lb loaded, which puts it in Minn Kota's 30–40 lb row. Step up to 55 lb if you fish wind or current.

What size trolling motor do I need for a 16 foot boat?

40–55 lb on 12V for most 16 ft boats, since Minn Kota's chart puts 16–17 ft boats at 1,600–2,599 lb. If your loaded weight is over 2,600 lb, move to a 24V motor with 70 lb or more.

Can a trolling motor be too powerful for a small boat?

Extra thrust isn't the problem; you can always run a bigger motor at a lower speed. The costs are the motor's weight and, above 55 lb, a second battery for 24V. On a canoe or kayak those extra pounds matter more than the extra thrust.

How long is a trolling motor shaft supposed to be?

Long enough to put the center of the motor and the prop tip at least 12 inches underwater, per Minn Kota. Measure from the mount to the waterline with the boat loaded, then use the transom or bow chart above.

Is the 2 lb per 100 lb rule right?

It's a rough starting point. Bass Pro's version works out to 2.5 lb per 100 lb, and Minn Kota's chart sets a 30 lb minimum for anything under 1,600 lb. Use the formula to check, and the chart to decide.

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The Bottom Line

Weigh your loaded boat, read the thrust and voltage off Minn Kota's chart, and add thrust for wind or current. Then pick the shaft length from the transom or bow height. For most kayaks, canoes and jon boats that means a 12V motor of 30–55 lb on a 30–36 inch shaft. The Minn Kota Endura C2 30 covers the light end and the Newport NV-Series 55 lb the windy end. Move to 24V only when your loaded weight passes about 2,600 lb. If you're fitting one to a kayak, our kayak trolling motor installation guide covers mounts and wiring.