Noise from propshaft?

[Sdtimbercruzer]

Hi All,

Took Heidi, 28ft timber cruiser for my first big adventure. 40km moving from Pittwater to Sydney harbour, her new home. All went well until I quite literally got under the sydney harbour bridge. All of a sudden a noise started from what sounded as it it was coming from propshaft. Powered down and it stopped . Power on and it started again. Every time a boat would pass and wash would move around the noise got louder then went away, came back again.

I have a video: https://youtu.be/fjYevB1SJtk

Sound at 4 sec 10 sec and 13 sec.

Shaft gland had a constant water trickle after the trip which I stopped by tightening (know it needs to weep so didn't tighten too much but enough to stop contstant trickle when engine was off) once on home mooring. Didn't get a chance to see if noise went following that as yet. But any ideas? Searching on this sight suggests cutless bearing I believe.


Some photos attached too.

Many thanks

[paulajayne]

I would check the cutlass bearing.

[Searles]

Firstly check engine mounts ,are they firm or soft or loose,if solid mounted check engine Bed bolts ,if you can reach the shaft feel if it’s loose or wobbly ,check g/ box oil level ,probably a simple answer .⛵️⚓️

[Sdtimbercruzer]

Originally Posted by Searles

Firstly check engine mounts ,are they firm or soft or loose,if solid mounted check engine Bed bolts ,if you can reach the shaft feel if it’s loose or wobbly ,check g/ box oil level ,probably a simple answer .⛵️⚓️

Thanks will do. Appreciate the reply

[tkeithlu]

Something it out of balance or loose. The question is what, and you've gotten some suggestions as to what. When "right," the entire chain from engine mount to propeller blade is firm, balanced, held in place, and spins smoothly.

So, you start at one end and move to the other. If it's convenient, you start at the prop end, because that's the more likely source, but it's underwater so it may be worthwhile to eliminate the inside the boat sources before the problems of pulling the boat or diving to inspect.

Sources that come to mind at the moment, starting at the mounts: broken, soft, or slipped engine mount(s); loose mounting arm on the engine; loose bolts at the transmission/engine; broken thrust plate at the engine; loose tranny/shaft connection; loose flange on the shaft; misalignment of the shaft; bent shaft; worn out or loose Cutless bearing; rope around the prop shaft; loose propeller; bent or broken propeller.

Others may think of a few more.

Now, likelihoods'. From your description, something working loose or caught in the propeller seems most likely. You didn't hit anything, so a bent shaft or dinged propeller sound less likely. You can do a general check on internal looseness by running the engine in gear, carefully, while tied to the dock. See whether anything moves while the shaft turns. The engine running and the engine not running should look about the same - if it shakes, something is loose, bent, or both. If all is tight, it's likely time to take a look underneath. See if there is rope, a ding in the prop, or looseness down there.

Detective job. You'll figure it out, repair it, and go sailing.

[Sdtimbercruzer]

Originally Posted by tkeithlu

Something it out of balance or loose. The question is what, and you've gotten some suggestions as to what. When "right," the entire chain from engine mount to propeller blade is firm, balanced, held in place, and spins smoothly.

So, you start at one end and move to the other. If it's convenient, you start at the prop end, because that's the more likely source, but it's underwater so it may be worthwhile to eliminate the inside the boat sources before the problems of pulling the boat or diving to inspect.

Sources that come to mind at the moment, starting at the mounts: broken, soft, or slipped engine mount(s); loose mounting arm on the engine; loose bolts at the transmission/engine; broken thrust plate at the engine; loose tranny/shaft connection; loose flange on the shaft; misalignment of the shaft; bent shaft; worn out or loose Cutless bearing; rope around the prop shaft; loose propeller; bent or broken propeller.

Others may think of a few more.

Now, likelihoods'. From your description, something working loose or caught in the propeller seems most likely. You didn't hit anything, so a bent shaft or dinged propeller sound less likely. You can do a general check on internal looseness by running the engine in gear, carefully, while tied to the dock. See whether anything moves while the shaft turns. The engine running and the engine not running should look about the same - if it shakes, something is loose, bent, or both. If all is tight, it's likely time to take a look underneath. See if there is rope, a ding in the prop, or looseness down there.

Detective job. You'll figure it out, repair it, and go sailing.

Thanks tkeithlu, very thorough reply and plan. Heading to the boat tomorrow and see what I can find. Thanks again!

[Sdtimbercruzer]

Originally Posted by Sdtimbercruzer

Thanks tkeithlu, very thorough reply and plan. Heading to the boat tomorrow and see what I can find. Thanks again!

Update here. Seems to be fixed. Approached as tkeithlu said, starting at engine mounts (as she is on a swing mooring). Found that the propeller shaft, north of the gland where it is claimed down (transmission coupling? ) was loose and slipping. Tightened and noise stopped. For now at least. Not sure why wake from other boats affected it before the believed fix but eill keep an eye on it. Thanks again for the ideas and plan.

[tkeithlu]

Good work! It was likely to be a single source, and you found it without disassembling the entire boat. Possibly the wave of water pressure from a passing boat against the propeller shifted the shaft at the loose connection?

[Bill O]

Has your wooden boat been out of the water for a while? If so, would check the alignment after it has had a proper time for the timber to swell back up.