Cutlass bearing replacement: symptoms, cost and how it's done
A cutlass bearing gives years of quiet service, then starts telling you it's done — a rumble under power, a vibration that builds with the revs, a knock at the shaft. Here's how to confirm the bearing is worn, what the job really costs, and how to order the right replacement before the boat comes out of the water.
When to replace a cutlass bearing: the symptoms
A cutlass bearing is a water-lubricated shaft bearing: the propeller shaft rides on a thin film of seawater inside a grooved liner, and the grooves flush grit through instead of letting it grind the shaft. (New to the part? Start with what a cutlass bearing is.) As the liner wears, the clearance opens up and the shaft starts moving where it shouldn't. The classic signs of cutlass bearing wear:
- Rumble or clunk under power — most noticeable coming on or off the throttle, as the shaft shifts across the worn clearance.
- Vibration through the hull that builds with engine revs and wasn't there last season.
- Visible shaft movement when the shaft is levered at the bearing with the boat out of the water.
Any one of these is a prompt to check. All three together means the bearing is overdue — and a worn bearing lets the shaft run untrue, which accelerates wear on the shaft itself, a far more expensive part to replace.
The shaft-wiggle test
The definitive check costs nothing and takes ten seconds. With the boat out of the water, grab the propeller shaft right at the propeller and try to move it up and down. A healthy bearing allows no perceptible movement — the running clearance is only thousandths of an inch. If you can feel a knock, or see the shaft move inside the bearing, the bearing is due for replacement.
Make it a habit at every haul-out, even if the boat feels fine underway. Catching a worn bearing while the boat is already on the hard is exactly the cheap, convenient moment to deal with it.
How long does a cutlass bearing last?
Many years. Most owners see 5–10 or more from a bearing, depending on engine hours, how gritty the water is, and how well the shaft is aligned. Sandy or silty water shortens life — suspended particles are the abrasive that wears the liner. If your boat lives in that sort of water, a rubber cutlass bearing is worth considering: its longitudinal water grooves flush particles through rather than letting them grind. Poor engine alignment is the other killer — it loads one edge of the bearing and chews through it early. Wear is gradual, so a quick wiggle test each season is all the monitoring the bearing needs.
Cutlass bearing replacement cost
Honest answer: the bearing is the cheap part of the job. Here's how the cost breaks down.
| Item | What to expect |
|---|---|
| The bearing | $115 – $2,395 inc GST across our 215-size Exalto range. Most common sizes land between roughly $200 and $500 — find yours on the size chart. |
| Haul-out / slipway | Set by the yard. The boat must come out of the water — there's no in-water method. |
| Yard labour | Varies by yard, and by whether the propeller shaft has to be drawn to get at the bearing. A strut bearing with easy access is a much shorter job than a stern-tube bearing behind a coupling. |
Because the haul-out dominates the bill, the smart move is bundling: do the antifoul, anodes and shaft seal in the same lift. If the shaft is being disturbed anyway, it's the ideal time to replace the shaft seal too — our sister store PSS Seals Australia supplies PSS dripless shaft seals for exactly this job. One haul-out, one bill, a whole drivetrain refreshed.
How to replace a cutlass bearing
The process itself is simple in outline. The propeller comes off, and depending on where the bearing sits — stern tube, strut, P-bracket or skeg — the shaft may need to be drawn. The old bearing is then extracted: it's held by a press fit and often adhesive, so it's pressed out with a puller, or cut and collapsed inward first. The seat is cleaned and measured, and the new bearing is pressed in.
For most owners this is a yard job, and rightly so. DIY is possible if you have a proper bearing puller and a careful hand — the risk is scoring or distorting the stern tube during extraction, which turns a bearing swap into machining work. If the housing is already worn or slightly oversize, a brass-shelled bearing gives the metal shell's grip where a plain bearing would sit loose.
Ordering the right replacement
Measure first, order second. A cutlass bearing is specified by three numbers — shaft inside diameter (I/D), housing outside diameter (O/D), and overall length — and our measuring guide shows how to take each one. Two rules save the most grief:
- Never pull the old bearing just to read it. Extraction usually destroys the bearing and the part code stamped on it. Measure the shaft and housing directly instead.
- Never add clearance yourself. Exalto's published tolerances already build in the running clearance on the I/D and the interference fit on the O/D.
Match your three numbers to a row on the size chart —
215 sizes from 3/4″ (20 mm) up to 4″ (100 mm) shaft diameter, in fully metric
(MPSF50), metric-shaft/imperial-housing (MIPSF40) and fully imperial
(IPSF20) part-code systems. For most boats in clean coastal water, a
phenolic bearing is the modern default. And if the old bearing
is a Johnson Cutless® part, cross-reference by dimensions, not part codes — here's
how the two ranges line up.
Order the bearing before the boat comes out
Yard time is expensive — don't let it tick by waiting on a part. We ship genuine Exalto cutlass bearings from Australian stock with free Express Post Australia-wide. Order an in-stock size before 2pm AEST and it's dispatched the same day; sizes not on the shelf ship in 3–4 weeks, so measure and order well ahead of your haul-out date. Every price includes GST.
Find your size on the chart Email us your measurements
Not sure which bearing you need? Send us your shaft diameter, housing bore and seat length via the contact page and we'll reply with a specific Exalto part-code recommendation.
Cutlass bearing replacement FAQs
How much does cutlass bearing replacement cost?
The bearing itself costs $115 to $2,395 AUD including GST depending on size, with most common sizes between roughly $200 and $500. On top of that come the haul-out and yard labour, which vary by yard and by whether the propeller shaft has to be drawn. The bearing is usually the cheap part of the job, so most owners bundle it with antifoul, anode and shaft seal work in the same haul-out.
When should a cutlass bearing be replaced?
Replace it when you notice a rumble or clunk under power, vibration through the hull that builds with revs, or shaft movement at the bearing. The definitive check is the shaft-wiggle test: with the boat out of the water, grab the propeller shaft at the propeller and try to move it up and down — any perceptible knock or movement means the bearing is due.
How long does a cutlass bearing last?
Commonly 5–10 years or more, depending on engine hours, how gritty the water is, and shaft alignment. Sandy or silty water shortens bearing life, and poor engine alignment wears one edge of the bearing early. A quick shaft-wiggle test at each haul-out is all the monitoring it needs.
Can I replace a cutlass bearing myself?
It's a haul-out job either way — the boat must be out of the water. DIY is possible with a proper bearing puller and care not to score or distort the stern tube during extraction, but for most owners it's a yard job: the old bearing is pressed or cut out and the new one pressed in, usually alongside other haul-out work.