Jp3 propeller dilemma

[Capella247]

Great result.   The 24 x 22 works great .  Boat accelerates and stops much better - but that might just the bonus of 3 blades.  It flies into locks.   Ticks over ok as well.  Probably should be bigger for the engine but don't think I could comfortably fit a bigger diameter or pitch without shaving more off the rudder.     A lot smoother  on the tiller as you can imagine.  However still have the low rev knock at very low tick over and this sounds like it is coming from closer to the engine so maybe the drive plate has gone.  Would surprise me if something isn't out.  It's clear from the prop the blade has missing for some time the break is fairly tarnished.  Have ordered tachometer so next step is to work out reduction ratio.   Cheers tom

[alan_fincher]

So I can't resist asking......

Given your user name, do you also own the butty Capella, as well as the boat you are asking about here?

[RLWP]

1 hour ago, Capella247 said:

Great result.   The 24 x 22 works great .  Boat accelerates and stops much better - but that might just the bonus of 3 blades.  It flies into locks.   Ticks over ok as well.  Probably should be bigger for the engine but don't think I could comfortably fit a bigger diameter or pitch without shaving more off the rudder.     A lot smoother  on the tiller as you can imagine.  However still have the low rev knock at very low tick over and this sounds like it is coming from closer to the engine so maybe the drive plate has gone.  Would surprise me if something isn't out.  It's clear from the prop the blade has missing for some time the break is fairly tarnished.  Have ordered tachometer so next step is to work out reduction ratio.   Cheers tom

You have a JP3 with a driveplate?

[David Mack]

36 minutes ago, RLWP said:

You have a JP3 with a driveplate?

Quite likely I would have thought if this is an industrial engine. The marine ones were fitted with a Blackstone box but this has a velvet drive.

[BWM]

12 hours ago, Capella247 said:

Great result.   The 24 x 22 works great .  Boat accelerates and stops much better - but that might just the bonus of 3 blades.  It flies into locks.   Ticks over ok as well.  Probably should be bigger for the engine but don't think I could comfortably fit a bigger diameter or pitch without shaving more off the rudder.     A lot smoother  on the tiller as you can imagine.  However still have the low rev knock at very low tick over and this sounds like it is coming from closer to the engine so maybe the drive plate has gone.  Would surprise me if something isn't out.  It's clear from the prop the blade has missing for some time the break is fairly tarnished.  Have ordered tachometer so next step is to work out reduction ratio.   Cheers tom

If the blade had been missing for some time it would very likely have caused wear to some of the stern gear, if it's knocking I'd expect to see or feel movement in whatever is worn. Did you check the bearing when out of the water?

[Capella247]

13 hours ago, alan_fincher said:

So I can't resist asking......

Given your user name, do you also own the butty Capella, as well as the boat you are asking about here?

Hi Alan, former owner of Capella now.  Sold her in July after 13 odd years of living on her.   I bought this tug as an interim replacement as now home is in Lancashire and we want to explore the north.  It's part of a grand and probably unrealistic scheme to own another historic boat in the future! 

[Capella247]

1 hour ago, BWM said:

If the blade had been missing for some time it would very likely have caused wear to some of the stern gear, if it's knocking I'd expect to see or feel movement in whatever is worn. Did you check the bearing when out of the water?

There wasn't any obvious sign of play according to the yard.   Although as you can imagine this was a quick fix.  I'm due back to there in the spring early summer so will sort then. 

12 hours ago, David Mack said:

Quite likely I would have thought if this is an industrial engine. The marine ones were fitted with a Blackstone box but this has a velvet drive.

That's right this is an industrial unit and everything is back to front.  But it runs well.   I'm only going from online images of what a drive plate looks like,   but there does appear to be one.