Grinding noise when in gear

[christopherb]

My boat is a Maurice Griffiths Kylix with a Volvo Penta MD11C and a Volvo Penta MS gearbox. When I engage gear, there is a grinding noise that seems to come from the stern of the boat. I've checked the obvious things: nothing fouling the propeller, gearbox has oil which looks clean with no swarf that might indicate worn teeth or bearings, the engine mounts seem good and the prop turns freely by hand (she's still in the water but in a mud berth so the propeller is exposed at low water). The previous owner suggested that there might be grit in the cutless bearing. Grinding noise today What could it be?

 

[Plum]

My boat is a Maurice Griffiths Kylix with a Volvo Penta MD11C and a Volvo Penta MS gearbox. When I engage gear, there is a grinding noise that seems to come from the stern of the boat. I've checked the obvious things: nothing fouling the propeller, gearbox has oil which looks clean with no swarf that might indicate worn teeth or bearings, the engine mounts seem good and the prop turns freely by hand (she's still in the water but in a mud berth so the propeller is exposed at low water). The previous owner suggested that there might be grit in the cutless bearing. Grinding noise today What could it be?

Your link, which I assume is a sound recording, does not let me have access.. After you engage gear, does the noise change or go away as you gently increase speed?

 

[christopherb]

Your link, which I assume is a sound recording, does not let me have access.. After you engage gear, does the noise change or go away as you gently increase speed?

I'll check that the link has permissions, It seems to be more or less constant.

 

[Tranona]

That is possible. Normally the cutless is water cooled with the water flow coming from forward motion. So sitting in a mud berth could well result in the bearing being clogged with mud. Probably best to wait until you haul the boat and investigate what sort of bearing type you have. The term "cutless" tends to be used generically but there are different types of bearing such as white metal, rubber, composite as examples. If it is a fluted bearing like a cutless there is also the possibility of crevice corrosion of the stainless shaft where mud packed flutes are the sort of conditions where it can occur.

Nice boat you have - I saw it advertised. I have a Golden Hind, my second MG designed boat. Previous one was one of the original Eventide 26s. The Kylix was on my list when I was looking last time, but it was the 29 that I wanted and that was sold before I was in a position to buy.

 

[christopherb]

I'll check that the link has permissions, It seems to be more or less constant.

Check the link now please. I've given permission to anyone with the link.

 

[Tranona]

I have listened to it but not eay to tell just from the sound. do you have photos of the stern gear at both ends - that is the inboard sealing arrangement and the outboard bearing?

 

[christopherb]

That is possible. Normally the cutless is water cooled with the water flow coming from forward motion. So sitting in a mud berth could well result in the bearing being clogged with mud. Probably best to wait until you haul the boat and investigate what sort of bearing type you have. The term "cutless" tends to be used generically but there are different types of bearing such as white metal, rubber, composite as examples. If it is a fluted bearing like a cutless there is also the possibility of crevice corrosion of the stainless shaft where mud packed flutes are the sort of conditions where it can occur.

Nice boat you have - I saw it advertised. I have a Golden Hind, my second MG designed boat. Previous one was one of the original Eventide 26s. The Kylix was on my list when I was looking last time, but it was the 29 that I wanted and that was sold before I was in a position to buy.

I just looked at the survey and it says 'a butyl rubber cutless bearing' with about 1mm play, which I guess could let grit and small fragments of shell in, leading to the noise.

 

[christopherb]

I have listened to it but not eay to tell just from the sound. do you have photos of the stern gear at both ends - that is the inboard sealing arrangement and the outboard bearing?

Screenshot Try that, from the survey report.

 

[Jules W]

Have you tried disconnecting the shaft and trying it to check it's not the gear box. We had a gear box issue which I would have sworn was a noise from the prop end, but it must have been vibration. Also do you have a shaft anode which might be loose?

 

[Tranona]

Thanks for that. Inboard end is pretty standard stuffing box with grease feed. That should be OK if the shaft turns freely. The photo of the prop unfortunately does not show the crucial area which is the gap between the front of the prop boss and the end of the bearing housing. From the perspective of the shot it looks like there is not much of a gap - there should be a minimum of 15mm, preferably 20mm to let the water flow in and out. It also looks like the might be scoops or slots in the housing to let water in. The gap also allows the shaft to move in and out as the engine moves when you engage gear.

 

[Supertramp]

I had a lot of noise from my propshaft last season which was very noticeable when freewheeling the prop and sailing fast (5-6 knts). Mine had about 1-2mm play when dried out. Play is hard to judge as it can be tighter when wet. I'm surprised the noise does not change with shaft speed or direction - mine was always quiet at low speeds. Not clear if you have a packed stern gland or dripless seal.

I replaced the cutlass (ribbed butyl rubber) and it made a big difference. Replacing was relatively straightforward if a bit of a voyage of discovery. It did let me clean a lot of scale off the shaft

 

[christopherb]

Have you tried disconnecting the shaft and trying it to check it's not the gear box. We had a gear box issue which I would have sworn was a noise from the prop end, but it must have been vibration. Also do you have a shaft anode which might be loose?

I have checked the shaft anode which is secure. I might try disconnecting the shaft, thanks for the suggestion.

 

[christopherb]

I had a lot of noise from my propshaft last season which was very noticeable when freewheeling the prop and sailing fast (5-6 knts). Mine had about 1-2mm play when dried out. Play is hard to judge as it can be tighter when wet. I'm surprised the noise does not change with shaft speed or direction - mine was always quiet at low speeds. Not clear if you have a packed stern gland or dripless seal.

I replaced the cutlass (ribbed butyl rubber) and it made a big difference. Replacing was relatively straightforward if a bit of a voyage of discovery. It did let me clean a lot of scale off the shaft

It's a packed gland as shown in the photo from the survey, The recording was done while the boat was moored in the marina, but last time I went out in it it was I think less harsh and intermittent.

 

[christopherb]

I think it will turn out to be the cutless bearing.

 

[Tranona]

I have checked the shaft anode which is secure. I might try disconnecting the shaft, thanks for the suggestion.

do you have an anode on the shaft between the prop and bearing housing? If so this may be a mistake. Shaft anodes are for stern gear that as exposed shafts such as those running in a P bracket. On the type of stern gear you have the best way of getting an anode in the circuit is a hull anode connected to the shaft through the gearbox. This leaves the exposed shaft clear for water to enter the bearing. Photos of my boat showing how the anode is mounted in the first one and the gap in front of the propeller in the second.

 

[Jules W]

The other thing to check is if your rope cutter has plastic spacers (my ambassador rope cutter does). These can wear over time. Mine developed a noticeable clicking noise as it was catching. You could take it off and see if the noise persists

 

[Tranona]

The other thing to check is if your rope cutter has plastic spacers (my ambassador rope cutter does). These can wear over time. Mine developed a noticeable clicking noise as it was catching. You could take it off and see if the noise persists

See the photos in post#8. No Stripper fitted

 

[Jules W]

Sorry. I was confused by post 15 which i now realise wasn't your boat. I would definitely try disconnecting the shaft and running it to double check if it could be the gear box. If not then i think it will need a new bearing. Not sure of your set up. We have a long shaft through a longish tube to a p bracket. We have the normal p bracket bearing plus an additional half bearing in the tube? Could a previous owner have fitted sinething similar to yours? Could something like that be catching? It would need the shaft pulling to check

 

[justanothersailboat]

It didn't sound exactly the same as yours, but I had a problem with a worn cutless bearing combined with imperfect alignment this year that lead to a periodic rumbling grinding noise, worse at different RPM and (at low revs - high not tested!) different when going along vs. on the mooring. Have changed cutless and tweaked the alignment but not yet found out if this is a complete cure.

 

[lynnx22]

Does it do it in reverse?
If not, maybe prop is pushing into cutlass face under power?
Some boxes let the shaft move whilst changing gear.
Just a thought ...