Prop Shaft Alignment & Strut Bearing (Cutless) Replacement
Eliminate the
Vibration.
If your boat shakes, your drivetrain is fighting itself. We combine strut bearing replacement with precision in-water alignment to make your inboard propulsion silky smooth.
The "Cutless" Bearing
Located in the strut under the boat, this rubber-lined brass sleeve supports the prop shaft. When it wears out, the shaft wobbles, causing a deep rumble or vibration that shakes the floorboards.
0.003" Tolerance
We align the engine coupling to the shaft coupling within three-thousandths of an inch. That is thinner than a sheet of paper. This precision prevents transmission seal failure.
In-Water Logic
Boats flex when on land. Aligning an engine while the boat is on a trailer is useless. We perform the final alignment 24 hours after launch, once the hull has settled in the water.
Precision Protocol.
A multi-stage process for perfect geometry.
Haul & Replace
While the boat is out of the water, we remove the prop and use a hydraulic press to replace the worn cutless bearing in the strut.
Launch & Settle
We launch the boat and let it sit for at least 24 hours. This allows the fiberglass hull to relax into its natural shape.
Measure Gap
We disconnect the shaft coupling and use feeler gauges to measure the gap at the top, bottom, and sides (Face Alignment).
Adjust Mounts
We adjust the engine motor mounts up, down, or sideways until the coupling gap is less than 0.003" all around.
Smooth Sailing.
Protect your transmission from destruction.
Materials & Tolerances.
We adhere to ABYC P-6 guidelines.
Common Questions
How long do bearings last?
In clean water, a cutless bearing can last 500-1000 hours. In sandy water (like running aground), it can be destroyed in minutes. If there is "play" in the shaft, it's time.
Why is it vibrating?
Vibration is usually caused by: 1) A bent prop, 2) A worn cutless bearing, or 3) Engine misalignment. We check all three to find the root cause.