Power delivery issue

[Viscount]

Sealing 285, 2 x AD31, 290DPs.

Went out today and couldn't plane initially so tried each side in turn. Port got 2,500 RPM with about 8 KTS (normal for the boat); starboard got 3,500 RPM with about 6 KTS. Due to an assumed unrelated issue I couldn't lift the starboard drive to see if any issues there; relays were engaging but pump motor wasn't playing. So, anyway, the question is what could cause a seeming slippage in the linkage between the starboard engine and the props?

 

[volvopaul]

Sealing 285, 2 x AD31, 290DPs.

Went out today and couldn't plane initially so tried each side in turn. Port got 2,500 RPM with about 8 KTS (normal for the boat); starboard got 3,500 RPM with about 6 KTS. Due to an assumed unrelated issue I couldn't lift the starboard drive to see if any issues there; relays were engaging but pump motor wasn't playing. So, anyway, the question is what could cause a seeming slippage in the linkage between the starboard engine and the props?

3500 is quite high for one engine on its own, on a trial I run each engine to max and only get around 2200/2400 rpm I'd say you have either a slipping drive cone or slipping prop hub.

 

[Momac]

.......................or a very smashed set of props?

 

[CX54WEK]

.......................or a very smashed set of props?

Which would give a lot of vibration.

 

[Stats007]

Cone clutch is likely culprit.

 

[Viscount]

There's no vibration.

Is the prop hub mentioned part of the propellor itself? I have spares so that would be an easy one.

What's involved in fixing the cone clutch.

Intending lifting boat ASAP for its annual anti-foul etc. anyway.

 

[Stats007]

It's a Volvo job and not cheap I'm afraid. I believe you can lap the cones without having to re-shim but all depends on how bad it has become. The drives are very sensitive to oil type so can be caused by that or a linkage problem.

 

[Viscount]

Thanks for all replies. Hoping it's a prop.....

 

[KevB]

One of the duo props fallen off.

 

[Chris_d]

One of the duo props fallen off.

Yes does sound like the back prop has come off !

 

[Viscount]

Thanks. That has happened before but the effect was nothing like as pronounced. Anyway, I won't be able to determine until either I get the drive lift pump working again or the boat comes out the water and both have to happen soon!

 

[Viscount]

Yep, it's a prop problem; I managed to get the drive lift working to see that the rear prop appears to have come off its bush. Cone nut is still present. Thanks to all for the replies.