Trolling Motor Thrust Calculator
Work out how many pounds of thrust your trolling motor needs from your boat's loaded weight, plus the right voltage and motor class.
How much trolling motor thrust do I need?
The accepted rule of thumb is 2 lbs of thrust for every 100 lbs of fully loaded boat weight — that's hull, motor, batteries, gear, fuel and people. If you regularly fish wind, current or open water, add 25–50% on top so the motor isn't working at its limit. As a practical floor, don't go below a 30 lb motor on anything bigger than a dinghy.
The thrust formula
Min thrust (lb) = (Loaded weight in lb ÷ 100) × 2
This calculator converts your weight from kilograms, applies the rule, adds a margin for conditions, and rounds up to the nearest real motor class.
Thrust, voltage and motor class
| Thrust | System voltage | Suits |
|---|---|---|
| 30–45 lb | 12V | Dinghies, kayaks, small tinnies |
| 55–80 lb | 24V | 4–5 m tinnies & small fibreglass boats |
| 101–112 lb | 36V | Heavier bass / bay boats & pontoons |
Don't forget the battery
More thrust draws more current, so size the battery bank to match your fishing session. Work out runtime and capacity with the battery sizing calculator, the current draw calculator, or estimate distance with the electric boat range calculator.
Note: thrust (static pull) is not horsepower. The hp figure here is an approximation (~1 hp ≈ 50 lb of static thrust) for comparison only.
Frequently Asked Questions
How many pounds of thrust do I need for my boat?
The standard rule is 2 lbs of thrust for every 100 lbs of fully loaded boat weight. A 600 kg (1,320 lb) loaded boat needs around 26 lbs minimum — so a 30 lb motor in calm water, stepping up to 45–55 lbs if you fish wind or current. It's always better to have spare thrust than to run a small motor at full power.
Does more thrust mean a faster boat?
Not really. Trolling motors are designed for slow, controlled positioning, not speed — most top out around 4–5 knots regardless of thrust. Extra thrust gives you control against wind and current and longer battery life at part throttle, not a higher top speed.
What voltage trolling motor should I choose?
Thrust rating drives the voltage: up to about 45 lbs is 12V (one battery), 55–80 lbs is usually 24V (two batteries), and 101–112 lbs is 36V (three batteries). Higher-voltage systems draw less current for the same power, so they run longer and cooler.