A boat that will not get on plane is usually short of thrust or carrying the bow too high: too much weight, weight too far aft, a prop with too much pitch or a damaged hub, the motor trimmed out, too little horsepower for the hull, or an engine that is not reaching its rated rpm. Start by checking the load, trimming the motor all the way down and confirming the engine reaches its wide-open throttle rpm range.
Common causes
| Cause | Clues |
|---|---|
| Overloaded or weight aft | Bow rises high and stays there |
| Motor trimmed out | Bow climbs, boat plows; trim down to get on plane |
| Prop pitch too high | Engine cannot reach rated rpm at full throttle |
| Spun prop hub | Engine revs up but the boat barely accelerates |
| Damaged prop | Vibration, lost bite |
| Not enough horsepower | Boat at or above its rated load with a small motor; see what size outboard |
| Engine not making power | Low rpm, rough running; see outboard runs rough |
| Fouled hull | Weeds or growth on the bottom add drag |
Check the rpm first
At wide-open throttle, the engine should reach the rpm range in its manual. If it falls short, the prop pitch is too high or the engine has a problem; if it over-revs without speed, the prop may be slipping or ventilating. Our prop slip and boat speed calculator helps compare expected and actual speed.
Runs fine but won’t get on plane
If the engine sounds healthy and reaches rpm but the boat will not plane, look at weight distribution, trim and the prop. Moving weight forward, trimming fully down and trying a lower-pitch or four-blade prop are the usual next steps; see the propeller sizing guide.
Spun hub
Many props have a rubber or replaceable hub that can slip after a strike or with age. The engine revs but the boat does not push; replacing the hub or prop fixes it.
Help it plane
- Trim tabs or a hydrofoil push the bow down and shorten time to plane; see boat porpoising.
- Keep the hull clean and the load forward.
- Choose the prop for the load you actually carry.
Too little motor?
If the boat is loaded near capacity and the motor is well below the capacity plate rating, a larger motor may be the real answer; compare models on our outboard motors by horsepower page and see our boat propellers.
More guides: outboard trim not working · outboard loses power at full throttle · 20 vs 25 HP outboards · spun prop hub · prop slip · how to tell if a prop is bent.
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