Any ideas?

[Ricco1]

I've had 2 issues reported to me about my day hire boat in the past 2 days.

 

On Sunday a customer reported a grinding noise from somewhere near the back of the boat. It lasted a minute or two then stopped. This was when going through the narrow gap just before Bugsworth Basin.

 

Today the customer reported that there was vibration coming from somewhere around the gearbox/ propshaft/ propeller area. This was only apparent at just below full speed.

 

On each occasion I checked the propeller, it was clear. The prop itself, whilst not in perfect condition isn't too bad, no worse than it's been for a year. So I've ruled out prop shake. I've checked the engine and gearbox oil levels, all fine. I tried to recreate the reported vibration today but was unable to do so, it sounded normal at all engine speeds, when in gear.

 

It's approaching the busiest part of the year, I'd rather sort out any problem now rather than wait for a potential breakdown. I'm wondering whether there is a problem with the gearbox. Do they normally just go, or is what's been reported perhaps a warning of things to come?

 

Any other ideas?

 

Isuzu 42 with a PRM 150 by the way.

 

Thanks

[Boredrider]

Is this the boat with a leak from the stern gear?

[Tony Brooks]

Could be anything from hydrophonic noise from the prop, ventilation, cavitation, prop too near the bottom & throwing muck about, or sympathetic vibration from another part of the boat. I suspect there is probably nothing wrong apart from the hirer's need for a idiot proof throttle stop.

 

If you have checked everything is tight and in fair order there is not much more that you can do until its more consistent. My no.1 choice would be from the first four above.

[PaulJ]

Aplogies if this is too obvious but is there much play on the prop shaft if you give the prop a good shake?

Or as you said the boat was going through a narrow bit (presumably at higher revs) either the trim of boat / hirers sat on front couldnt have caused a bit of air being sucked into prop maybe?

typed at same time but slower thsn tb!

Edited July 6, 2015 by PaulJ

[Alan Saunders]

The local day-hire boat from Devizes came past today at a very sensible speed. Half an hour later it had turned round and came past with a different helmsman, not much faster but with the engine/exhaust sounding much louder. I will bet that the tiller was juddering and there were all sorts of noises as the prop churned up the silt and debris from the bottom of the canal.

 

Alan

[Machpoint005]

The local day-hire boat from Devizes came past today at a very sensible speed. Half an hour later it had turned round and came past with a different helmsman, not much faster but with the engine/exhaust sounding much louder. I will bet that the tiller was juddering and there were all sorts of noises as the prop churned up the silt and debris from the bottom of the canal.

 

Alan

 

Not disagreeing but the highlighted bit might just be because the exhaust outlet is on one side?

My money's on the prop cavitation or mud churning explanations, though.