Drive problem.

Allan

Allan

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On the way back from my first sail of the year on Monday I found that I could only make a couple of knots under motor. I have a Westerly 33 with a 50hp Beta engine. The first thing I noticed was that, strangely, there seemed to be less vibration than I'm normally used to. When I looked down at the gearbox, in neutral, the drive coupling was turning slowly. It appeared to turn correctly when I put it in forward and reverse.
The things I can think of are:
Something around the prop.
Prop loose.
Propshaft loose in the drive coupling.
Is there anything else I need to check?
Allan
 
Allan said:
On the way back from my first sail of the year on Monday I found that I could only make a couple of knots under motor. I have a Westerly 33 with a 50hp Beta engine. The first thing I noticed was that, strangely, there seemed to be less vibration than I'm normally used to. When I looked down at the gearbox, in neutral, the drive coupling was turning slowly. It appeared to turn correctly when I put it in forward and reverse.
The things I can think of are:
Something around the prop.
Prop loose.
Propshaft loose in the drive coupling.
Is there anything else I need to check?
Allan
Click to expand...
Mine was like that year before last, all winter in the marina, the prop had turned in to a fuzzball of mussels!
Stu
 
"less vibration" seems to mean either the prop is turning more slowly for the revs (i.e. gearbox slipping) or the blades are furred up (so they don't enter dead water behind the keel).

Mysteriouser and mysteriouser...
 
sarabande said:
"less vibration" seems to mean either the prop is turning more slowly for the revs (i.e. gearbox slipping) or the blades are furred up (so they don't enter dead water behind the keel).

Mysteriouser and mysteriouser...
Click to expand...
I've never worked on a marine gearbox before. I have always imagined most were just simple versions of car gearboxes. Is there something that can slip?
Allan
PS I will post the result on here when I know the answer.
 
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Allan said:
I've never worked on a marine gearbox before. I have always imagined most were just simple versions of car gearboxes. Is there something that can slip?
Allan
PS I will post the result on here when I know the answer.
Click to expand...
The VP MS2 that I am used to is dead simple, a cone metal "clutch" connects the drive to a gear either for reverse or forward. The only slipping could be the cone BUT the drive forces the cones further in to "mesh" Very unlikely for them to slip.
Stu
 
skipper_stu said:
Tim
your search mostly brings up auto type ones with clutch plates in, they can slip relatively easy, his is a westerly, probably with a vp2003 and an mS2 box.
Stu
Click to expand...
As I said in my first post the engine is a Beta 50. I now believe the gearbox to be a PRM hydraulic type.
Allan
 
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If it is The small PRM box the clutch mechanism is a series of alternative plate with external splines interleaved with plates with internal splines compressing the the two sets together produces a solid drive with a mechanical engagement the larger boxes use hydraulic oil pressure
If its an oil operated box first thing to check is oil pressure (gearbox not engine)

Drain and check the oil for contamination either metallic filings or burnt residue.
Slipping can also be caused by incorrect lubricants
Never use adatives
 
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Your first post says you can't get any speed. That strongly suggests a fouled prop. The coupling (and presumably shaft) turning in neutral while you are sailing is normal, so probably red herring. If the box was slipping, the engine would be revving and the shaft not turning. Same would happen if the shaft was not tight in the coupling.

Gearboxes rarely give problems - fouled props are common so start with the easy bit first. Check the shaft is turning at the correct speed relative to engine revs and check the prop.
 
+1


You can see the shaft turning.(or at least the inside half of it) and we assume it didn't strike you as turning too slowly (or you would have said)
So it's something to do with the prop. did you leave the boat connected to the mains for a while, can you see the prop to count the blades?(assume not, or you would also be able to see abnormal growth)
Don't know the boat type, but possibly a crate of beer and some mates at the bow roller would bring the prop into view, then you can decide to go to the wall for a tide if needed.
 
Billjratt said:
+1 You can see the shaft turning.(or at least the inside half of it) and we assume it didn't strike you as turning too slowly (or you would have said)
So it's something to do with the prop. did you leave the boat connected to the mains for a while, can you see the prop to count the blades?(assume not, or you would also be able to see abnormal growth)
Don't know the boat type, but possibly a crate of beer and some mates at the bow roller would bring the prop into view, then you can decide to go to the wall for a tide if needed.
Click to expand...
I have to admit that I've never watched the flexy joint and shaft whilst motoring before, so I'm not sure if the speed was correct or not.
The boat is never left on the mains, all my power comes from wind, sun and the motor. I think (hope!) that if the prop was damaged enough to lose that much speed, any vibration would be increased, not reduced.
I think, with the weight of my boat, I would need most of the club on the bow to lift the stern!
I have planned to take the boat out of the water for her bi-annual clean up (only 9 months late). I should be able the problem when that happens in a couple of weeks.
Allan
 
Is your big engine making a lot of black smoke or is it spinning up to max revs too quickly ?? If it is smoking chances are that the prop is a ball of weed and mussels etc. If the engine is overrevving you probably have either a slipping cone in the box or the woodruff key has broken in the prop and is only gripping with friction.
Bit more info from your end may help.
Regards GOG
 
You can check the shaft is turning correctly by running it in gear while in your berth. It will be pretty obvious if it is slipping by observing what happens when you engage gear and rev the engine.
 
GrumpyOldGit said:
Is your big engine making a lot of black smoke or is it spinning up to max revs too quickly ?? If it is smoking chances are that the prop is a ball of weed and mussels etc. If the engine is overrevving you probably have either a slipping cone in the box or the woodruff key has broken in the prop and is only gripping with friction.
Bit more info from your end may help.
Regards GOG
Click to expand...
When I had the problem, just outside Cardiff barrage, I was more intent on getting a sail out to maintain steerage. There was no obvious smoke, if anything the revs came easier, but I'm not sure.
At present I'm hoping for something around the prop but think the prop key is top of my list. Some sort of slippage around the coupling/gearbox is still a possibility.
Many thanks for all the input, when I know more I will post again.
Allan
 
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