Axsail
How it worksFor SurveyorsFor OperatorsPricingGuidesAboutVisual Evidence ↗Coming soonStart free
FINDINGS LIBRARY · UNDERWATER GEAR

Loose P-bracket: how surveyors check a shaft strut and write it up

UPDATED 6 NOVEMBER 2026 · 3 EXAMPLE FINDINGS · 2 SOURCES

How a surveyor tells a loose P-bracket from a worn bearing, what moves when, what looseness does to the shaft and stern gear, what repair involves and three example findings graded A, B and C.

AT A GLANCE
Loose P-bracket
USUAL GRADE
A for a bracket that moves on the hull, or cracks in the hull round its base. B for movement at the bracket's fastenings or failed bedding with weeping inside. C for corroded fastenings on a bracket that doesn't move
FOUND WITH
Loading the shaft and the bracket by hand with the boat hauled and watching where the movement is, checking the base and fastenings inside, and looking for cracks round the base outside
JUDGED AGAINST
The bracket shouldn't move at all. Any play belongs in the bearing, and Good Old Boat treats more than 3/16 inch of bearing movement as too much
REPAIR COST
Rebedding and through-bolting a bracket, or glassing it back in, is yard work at haul-out. Alignment follows. Priced per boat

The P-bracket holds the propeller shaft out in the water near the propeller, bolted or glassed through the hull. It takes the propeller's thrust and every vibration. If its base or fastenings let go, the shaft runs out of line and the hull round the bracket starts to work.

How a surveyor checks it

With the boat hauled, load the propeller by hand up and down and side to side, and watch two things: the shaft in the bearing and the bracket on the hull. Movement in the bearing is a worn cutless bearing. Good Old Boat's Bill Sandifer uses a feeler gauge past 1/8 inch and calls more than 3/16 inch too much. Movement of the bracket itself is this finding.

Outside, look round the base for cracked gelcoat, failed bedding and rust or weeping. Inside, find the fastenings: PBO's Stu Davies notes on one boat the big issue was fixing the bracket's bottom bolt. Check nuts, backing plates and any wood backing, which softens when wet.

What decides the grade

The bracket shouldn't move at all. A bracket moving on the hull, or cracks round its base, is an A. Movement at the fastenings or failed bedding is a B. Corroded fastenings on a firm bracket are a C.

Loose P-bracket: example findings

The same defect written up at each grade, the way Axsail writes it from what the surveyor says on board. The grade follows what was found, so use these as wording, then grade what you see.

PROPULSIONA
P-bracket, propeller shaft

P-bracket moves on the hull when the propeller is loaded by hand. Gelcoat cracked round the bracket base outside; water weeping at the bracket bolts inside.

Recommendation: Do not run the engine in gear. Have the bracket removed, the hull round it repaired and the bracket rebedded and through-bolted with backing, then align the shaft, before the vessel is next used.

PROPULSIONB
P-bracket, propeller shaft

Slight movement at the bracket base when loaded firmly. Bedding compound at the base cracked. Bolts inside corroded. No cracks in the hull.

Recommendation: Rebed and refasten the P-bracket and check the alignment within 12 months, at the next haul-out.

PROPULSIONC
P-bracket, internal fastenings

Bracket firm on loading. Nuts inside lightly corroded.

Recommendation: Clean and protect the fastenings and check them at the next haul-out.

ASafety. Safety or compliance deficiency. Fix before the vessel is next underway.
B12 months. Deficiency that needs timely attention. Fix within about 12 months.
CRoutine. Note or observation, cosmetic or maintenance. Routine maintenance at the owner's convenience.

What repair involves

Job Reported cost
Rebed and through-bolt the bracket Yard labour at haul-out
Repair the hull laminate round the base Composite repairer, priced per boat
Replace backing or fastenings Parts and labour
Align engine to shaft after Mechanic's time

Bedding thickness moves the bracket, so alignment is checked after any rebed.

Photos to take

The bracket and its base outside, any cracks close up, the fastenings inside, and a short video of the movement. With Axsail, say what moved as you film and it goes on the propulsion finding.

Writing it up

Say whether the movement was in the bearing or the bracket, how much, the state of the base outside and the fastenings inside, and any weeping. Recommend the alignment check with any repair.

Frequently asked

What is a P-bracket?

The strut that holds the propeller shaft outside the hull, near the propeller. On many fin keel boats it carries the cutless bearing; Good Old Boat notes fin keel boats use bearings in the strut that supports the shaft.

How do I tell a loose P-bracket from a worn bearing?

Watch where the movement is. Load the propeller by hand. If the shaft moves in the bearing and the bracket stays still, it's the bearing. If the bracket moves on the hull, it's the bracket, and that's more serious.

How much play is too much?

In the bracket, none. In the bearing, Good Old Boat's Bill Sandifer says to check with a feeler gauge if the shaft moves more than 1/8 inch, and that more than 3/16 inch is too much.

What does a loose P-bracket do?

It lets the shaft run out of line. That wears the bearing, the shaft seal and the coupling, and a bracket moving in the hull opens a path for water through its fastening holes.

Your full survey report, minutes after the walk-round

Dictate as you inspect. Axsail builds the findings and the report for your signature

Start free

Related findings

Findings library
UNDERWATER GEAR

Worn cutless bearing

How a surveyor checks a cutless bearing for play, what 1/16 inch of movement means, what uneven wear says about alignment, what replacement involves and three example findings graded A, B and C.

How to find and write it up
ENGINE AND FUEL

Failed engine mounts

How to tell when marine engine mounts have failed, from rubber dust to a bracket sitting on the stud, how long they last, what new mounts cost, why alignment follows, and three example findings graded A, B and C.

How to find and write it up
UNDERWATER GEAR

Keel bolt corrosion

The signs of corroded keel bolts, why looking at the nuts isn't an inspection, when a bolt has to be pulled, what replacing keel bolts costs and three example findings graded A, B and C.

How to find and write it up
UNDERWATER GEAR

Seized seacocks

Why a seacock that won't close is a safety finding, how surveyors check seacocks and through-hulls, the ABYC strength test a ball valve on a through-hull can fail, replacement costs and three example findings graded A, B and C.

How to find and write it up
UNDERWATER GEAR

Leaking shaft seal

How many drips a stuffing box should make, when it needs repacking, what a surveyor checks on the shaft log hose, clamps and dripless seals, and three example findings graded A, B and C.

How to find and write it up
UNDERWATER GEAR

Depleted anodes

When sacrificial anodes need replacing, zinc, aluminium or magnesium for your water, what anodes that aren't wasting mean, what a surveyor checks and three example findings graded A, B and C.

How to find and write it up

Report templates with this finding

FREE TEMPLATE · WORD

Out of water survey

A free Word template for an out of water boat survey report: the hull below the waterline, moisture readings, running gear and through-hulls, with example wording and example findings graded A, B and C.

Open template
FREE TEMPLATE · WORD

Pre-purchase survey

A free Word template for a yacht pre-purchase survey report: every section explained, example wording, the sea trial and valuation, and example findings graded A, B and C.

Open template
FREE TEMPLATE · WORD

Sea trial report

A free Word template for a sea trial report: conditions and load, checks before departure, engine readings at each speed, systems tested under way, the engine room after the run, and example findings.

Open template

Related guides

YACHT SURVEYS · 7 MIN

Pre-purchase yacht survey: what it covers, how to book one and what to do with the report

What a pre-purchase boat survey covers, from the haul-out to the sea trial, how to choose a SAMS, NAMS, IIMS or YDSA surveyor, the survey contingency in your offer and how to use the report.