Seasick Ian
Active Member
Hi everyone,
I've been plagued with a chattering engine sound for a while, so i’m hoping to get some help figuring out what's causing it. Instead of trying to describe the sound, i've uploaded two videos:
The boat is a Leisure 23 with a Beta 14 engine, shaft driven, fixed 3-blade propeller and a dripless shaft seal. I had thought that it might be the shaft anode rattling around, but after taking off the anode, the sound still occurs. It's been on and off for a couple of years now, but lately it has gotten worse; louder and more frequent. The chatter is not present all the time, typically it doesn't occur at the start of a journey and usually when it develops a change in engine revs will make it dissipate, or sometimes it disappears unprompted. It also happens when the engine is switched off, with the propeller spinning freely as the boat sails along. Locking the shaft by engaging reverse gear stops the sound instantly, so it's not an engine sound exactly, it's related to the spinning of the propeller shaft. Heeling doesn't seem to make a difference. I had thought it might be the shaft bouncing around in the cutlass bearing as there was a lot of play so i replaced the cutlass bearing, but the sound remains. I’ve also repeatedly checked alignment and engine mounts. At this point I suspect the gearbox internals, maybe there is something loose i.e. broken gear tooth or bearing etc and sometimes it bounces around causing the sound, sometimes it doesn't. I also wonder if the dripless shaft seal might be causing it, but I can't see any sensible explanation for that. Or maybe the shaft isn’t centred and touches the side of the tube, but from eyeballing it, it looks ok.
Any thoughts? Something else completely?
I've been plagued with a chattering engine sound for a while, so i’m hoping to get some help figuring out what's causing it. Instead of trying to describe the sound, i've uploaded two videos:
The boat is a Leisure 23 with a Beta 14 engine, shaft driven, fixed 3-blade propeller and a dripless shaft seal. I had thought that it might be the shaft anode rattling around, but after taking off the anode, the sound still occurs. It's been on and off for a couple of years now, but lately it has gotten worse; louder and more frequent. The chatter is not present all the time, typically it doesn't occur at the start of a journey and usually when it develops a change in engine revs will make it dissipate, or sometimes it disappears unprompted. It also happens when the engine is switched off, with the propeller spinning freely as the boat sails along. Locking the shaft by engaging reverse gear stops the sound instantly, so it's not an engine sound exactly, it's related to the spinning of the propeller shaft. Heeling doesn't seem to make a difference. I had thought it might be the shaft bouncing around in the cutlass bearing as there was a lot of play so i replaced the cutlass bearing, but the sound remains. I’ve also repeatedly checked alignment and engine mounts. At this point I suspect the gearbox internals, maybe there is something loose i.e. broken gear tooth or bearing etc and sometimes it bounces around causing the sound, sometimes it doesn't. I also wonder if the dripless shaft seal might be causing it, but I can't see any sensible explanation for that. Or maybe the shaft isn’t centred and touches the side of the tube, but from eyeballing it, it looks ok.
Any thoughts? Something else completely?
