Volvo D2 55F - noise while sailing - engine off...?

[SP 111]

Hi all - after some advice on our engine pls. Have read many comments about similar engines but not this one. While sailing, we have started hearing a whirring noise, quite high pitched after a couple of hours sailing at 6+ knots. Never had this before, as far as I am aware. Concerned at what the noise was, I went below, opened engine compartment, and there was the noise coming from the engine . This was after about 2 hours of sailing. Engine still hot of course after motoring for 30 minutes out. My best guess is that it is the feathering prop rotating while we have the gear in neutral and the engine is off. Have seen lots of discussion around this on a Yanmar and other model engines, and some people say put the gear in reverse to stop the noise - this DOES indeed stop the noise on our yacht!! BUT, surely that cannot be good for the engine or the shaft or anything else? Sailing at +6 knots and having it in reverse - must damage something? And why is it happening in the first place, as i say, not had this issue in previous years. with the boat The engine was recently serviced about 2 months ago before the Greek sailing season began. I know not much at all about engines, and we are concerned for obvious reasons. Have read a lot of discussions, and opinions differ! Thanks!

 

[ithet]

Normally with a feathering prop you force it to feather by stoping engine in gear or putting in gear for a few seconds after stopping (in forwards). If the prop has feathered ok it should not rotate after then putting into neutral. There should be no need to use reverse. What propeller do you have and do you have a manual for it?

 

[VicS]

Follow the advice in your engine owners manual

Early editions say

When sailing the control lever should be in the neutral position if the boat is equipped with HS25 reverse gear. If the boat is equipped with S-drive or MS25 reverse gear the control lever should be the reverse position if a folding propeller is used and in neutral position if a fixed propeller is used​

The latest edition says

When sailing, set the control lever to astern if a folding propeller is fitted. If a fixed propeller is fitted the control lever should be set to neutral or reverse. When using a fixed propeller and sailing with the control lever set to reverse the speed is slowed down though less noise is being made​

​

(There are further instructions relating to a fixed blade propeller)

 

[Tranona]

Welcome.

You don't say whether it is a saildrive or a shaft drive. However what you are hearing is not from the engine but from the gearbox because the prop is turning. Around 6 knots is a common speed for this to start happening, but not common on a feathering or folding prop because by definition the shaft should not be turning when the blades are feathered or folded. It could be that one of the blades is sticking causing the shaft to turn as speed rises. As suggested it is best to stop the engine in gear so that the blades close. There is no harm in leaving it in gear if you prefer to stop the noise. Many do this with fixed blade props. Put it in reverse.

 

[neilf39]

My featherstream won't always completely feather if just put the engine in neutral so I briefly engage gear after the engine has stopped and that sorts it. I know if it hasn't as I hear the shaft rotating.

 

[SP 111]

Ok so this is going to make me look rather daft - but, forgive my age! I have just been advised by the yard it is now in fact a fixed propeller and not a feathering one! Sorry about that, Duff info provided! This is a sail drive model, as Tranoma asked. I must say there are some very knowledgeable people in this forum - thanks so much for the thoughts thus far!

 

[penfold]

If you have a feathering prop it will not feather reliably unless you put it in gear after the engine is stopped. Leaving it in gear with the engine stopped won't damage anything unless specifically prohibited by the operator's handbook. I've never encountered such an instruction but I've not experienced every possible boat engine type. Once the prop is feathered you could take it out of gear again if you wanted. Larger engines may have a hydraulic gearbox which won't shift with the engine stopped and can be damaged by freewheeling, they generally have shaft brakes(usually but not always automatic).

 

[dunedin]

With our D2-55, saildrive and folding prop, we always sail with locked in reverse.
However, out of mechanical sympathy, we try to let speed drop to 3 knots when it stops spinning, then put into reverse and speed up again.

 

[Bobc]

After stopping the engine, shove it in reverse for 5 seconds, and the back into neutral. This will help the prop to feather.

 

[VicS]

Ok so this is going to make me look rather daft - but, forgive my age! I have just been advised by the yard it is now in fact a fixed propeller and not a feathering one! Sorry about that, Duff info provided! This is a sail drive model, as Tranoma asked. I must say there are some very knowledgeable people in this forum - thanks so much for the thoughts thus far!

People seem not to have noticed this !

With a fixed prop the owners manual goes on from my earlier quote to say:-

IMPORTANT!​

If a fixed propeller is fitted the engine needs to be started and kept running for five minutes every fourth hour of sailing to avoid problems with the transmission system. The control lever must be set to neutral during the whole procedure.​

 

[penfold]

People seem not to have noticed this !

With a fixed prop the owners manual goes on from my earlier quote to say:-

IMPORTANT!​

If a fixed propeller is fitted the engine needs to be started and kept running for five minutes every fourth hour of sailing to avoid problems with the transmission system. The control lever must be set to neutral during the whole procedure.​

The OP posted more or less as I posted, so I could not read it. Who designs rubbish that is rendered unfit for purpose by not incorporating a shaft brake, what a farce.

 

[Tranona]

The OP posted more or less as I posted, so I could not read it. Who designs rubbish that is rendered unfit for purpose by not incorporating a shaft brake, what a farce.

Explain how you can fit a shaft brake in a saildrive which the OP has? This is a non problem. If you don't like the noise then put the drive into reverse as per the handbook. Owners of saildrive boats with fixed blade props have been doing this for years and there has hardly been an epidemic of failed drives.

On shaft brakes generally they were once popular to lock shafts so that 2 bladed props were vertical behind a long keel to reduce drag, but once folding and feathering props came in (and long keeled boats went out) they have disappeared. I remember designing one in the 80s but failed to find anyone interested in making it - "no demand". AFAIK there is now only one design available commercially in Germany.

 

[penfold]

Why is the handbook requiring the engine to be run 5 minutes in every 4 hours of sailing then? It's half-baked, if they fronted up and specified a gearbox that isn't going to melt while under sail or stated that a fixed prop cannot be used I'd have more respect.

 

[Tranona]

Why is the handbook requiring the engine to be run 5 minutes in every 4 hours of sailing then? It's half-baked, if they fronted up and specified a gearbox that isn't going to melt while under sail or stated that a fixed prop cannot be used I'd have more respect.

Usual Volvo covering their backs just like the 7 year replacement of saildrive diaphragms. The fact is these drives have been in use in their tens of thousands (mostly with fixed props) for nigh on 40 years and do not "melt".

As I said a non issue

 

[SP 111]

Hi folks, thank you so much for all of your thoughts, comments and advice, really appreciate you all taking the time to help. Having read all of this, the wife and I are sleeping much easier now thanks, and clearly it is a very common situation. We were sailing at about 4 knots yesterday and no noise at all, so it clearly is only when we get to around 6 that the issue appears. Putting into reverse gear does the trick - never knew that, and never had that issue before when we sailed on the boat last year, hence the call for advice! Thank you everyone and good sailing....