Noise in the saildrive 130s

[jo_que_se]

Hi fleet!

Please listen to the next video (Volvo 18HP + Saildrive 130s)

https://www.youtube.com/watch?v=3mydTXUDPaM

The first day after the service performed the oil change in the saildrive, We started to hear this noise . It is  very noticeable in the cockpit but it is very loud especially in the aft cabin:

The first thing I did was to check the oil level and saw that it was really low  (the meter was totally dry  )

I filled properly to the correct level, but the noise has not disappeared at all.

I think I was using engine for one hour more or less time until I reduced to 1500rpm and then appeared noise ... (squeaks like this only between 1400 and 1600 rpm)



Any idea what it could be? someone has experienced the same?

[Yngmar]

How much oil did you have to add to get to the right level?

The singing sound is typically associated with propellers, especially if it is only in a specific RPM range. Does it go away with higher RPM? Does it occur in reverse?

Did you get the propeller replaced or could it have been damaged during haulout? Was it antifouled?

If it goes away at higher RPM and does not occur in reverse, and there's no vibration indicating a seriously damaged propeller, it's probably just a singing propeller (have a google). Apart from the annoying noise, this is quite harmless and can supposedly be sorted out by filing the trailing edge of the blades. If the propeller was antifouled, it may stop doing it on its own as the paint on the edge wears off.

Did you raise this with the engineer who did the service? He should be interested, as he'd be the one I'd hold liable for damage occurred due to an underfilled saildrive (although you also should've checked the level before setting off).

[jo_que_se]

Hi Yngmar!

* It did that noise the first day after painting with antifouling, including the propeller !!!
* I added about 0.3 liters (less than 0.5 liters)
* It only squeals around 1500rpm. No noise at higher RPM...
* Didn't tested in reverse (yet..)
* I didn't noticed any special vibration

I've made another test:
while properly moored I tryed at different throttle positions and it didn't produce any noise (even in reverse). No noise at the "squealing" rpm and no noise in the full range of the engine ... So, it does it while the boat is moving without much efford. Does it point more to the singing propeller or not? 

The weird thing is that two days before than I went out sailing, I was with the operator in the moment of changing the oil and we both saw that he filled up to the correct level  (that's why I didn't checked it later). can it be possible that there was a kind of air bubble?

Today the mechanic has heard the noise and has started talking about changing two bearings of the transmission (but It didn't seemed to be very convinced...) 

Thank you for your answer!!

[Salty]

Just an observation, and it is that doing a test while your boat is securely moored will not replicate the conditions where you heard the noise from your saildrive. Instead what you have done is to substantially increase the loading on your engine and saildrive for a given rpm when compared with the situation while your boat was underway and slipping easily through the water rather than being restrained by mooring lines.
Yngmar was right to mention that you should have checked the oil level before you went out on that first occasion, so let's hope that nothing serious by way of internal damage has occurred to the workings of your saildrive. Boatyard engineers are not infallible, I had one reconnect my alternator wrongly but it has worked okay since he was called back to correct the situation. However, they should have known whether the oil they put into your saildrive was less than anticipated, and warned you to check it if it hadn't taken as much as it should, so think back to what your engineer said at the time, as any blame for damage may be difficult to apportion otherwise, and that's even if they accept any liability.
As for the "singing prop," if it didn't sing before the oil change, why should it sing now? The only time my prop made any noise was while sailing with the engine stopped and while I had a fixed propeller and had forgotten to leave it in gear. The forward movement of the boat would turn the propeller while it was in neutral, but this season I fitted a folding prop and so no more prop rotation while underway with the engine stopped and in neutral.

[jo_que_se]

I agree that the test while moored puts all the engine + saildrive under heavier load and the noise in not audible.

The sad thing is that the noise has appeared just after painting the boat (and the propeller) and after changing the oil . Both actions were done at the same time, so I'm not sure which one is the origin of the noise...

I've never heard about "singing propellers" but reading a bit on internet I find out that it makes also sense.

Both the engineer and me checked toghether the oil level at the moment of filling, but two days after the level had decreased. (weird too?)

[Nigel]

* It only squeals around 1500rpm. No noise at higher RPM...

In which case I think it is caused by propeller cavitation, so perhaps the oil is a red herring.

[Yngmar]

All of this points to just a singing propeller, probably caused by the antifouling paint changing the shape of the edge. It looks like you're in warm waters, so I'd hop in and have a look at the prop to ensure everything is alright there, and possibly take a putty knife and scrape the paint off the trailing edge of the blades, which might stop the singing.

The missing 0.3l of oil are about 10% of the total volume of a 130S. You're probably fine, although it may have caused some wear and shortened lifespan. No way to tell without stripping the whole gearbox down, so I'd just get on with sailing rather than doing that.

Unlike an engine, where all the oil you fill in just runs into a sump at the bottom, the saildrive is a narrow leg stuffed with a shaft and a box of gearwheels on top. That means the oil has to run past all of those bits down into the leg and around the corner, and it's quite easy to get an air bubble trapped somewhere, which is probably what happened with yours. It is advisable to put the saildrive into gear a few minutes and then turn off the engine and re-check oil level (let it settle about 10 minutes first). Also helps rotating the prop by hand (on the hard) with the gear in neutral while filling, although that's mostly for the 120S-E and its super goopy oil.

[jo_que_se]

Thank you for all you help, guys!

Do you think if, as a simple test, I go under water and put a sock (secured with a cable tie) on each blade in order to change its profile will give us a clue to determine that it's a problem of singing propeller???

BTW, I have to admit I'm really impressed about all your knowledge!!

[Kaptajnen]

The drop in oil level - if it happens again - might also be caused if the mechanic used the wrong size gasket at the bottom of the saildrive after he drained and re-filled the drive.

[Moodymike]

My previous boat a Moody 31 with shaft drive had a singing prop. Only occurred at 1500 revs at beginning of season when prop was clean. Did worry me until previous owner said had always done it.

[Nigel]

When I suspected cavitation I got towed behind the boat with dive gear on as the engine was wound up. At the critical point it looked like that bit in Star Wars when the Millennium Falcon finally jumps into hyperspace. I wish I'd taken a camera, much to dangerous to do again.

[Yngmar]

Do you think if, as a simple test, I go under water and put a sock (secured with a cable tie) on each blade in order to change its profile will give us a clue to determine that it's a problem of singing propeller???

At the very least it'll make a great story to tell! 

[jo_que_se]

 

[jo_que_se]

Last news!

Today I've tried the reverse gear and NO NOISE is heard at any rpm at all, even with the boat in movement, so it points again to bo a "singing propeller" case too.

This weekend I will try to perform the "socks-on-blades" test...

[Salty]

Hi Yngmar!

* It did that noise the first day after painting with antifouling, including the propeller !!!
* ...........
* It only squeals around 1500rpm. No noise at higher RPM...
* Didn't tested in reverse (yet..)
* I didn't noticed any special vibration

I have to admit that I was rather sceptical on the subject of this thread, until shortly after launching yesterday.
Over the winter I removed the folding prop fitted last year, and put back the fixed blade aluminium prop that came with the boat. There was nothing wrong with the folding prop tried out last year, it just didn't seem to make any appreciable difference over the original fixed blade prop. Well, not until this year👹
Having refitted the aluminium prop, I'd given it a gentle sanding down to remove any irregularities in the paint coating, then after priming it was given a coat of an aluminium friendly antifouling paint of a different type to that previously used and which left quite a shiny surface. Previous antifouling coatings had left a relatively rough surface.
Yesterday early afternoon the boat was launched and on my way to the sailing club mooring, a little over thirty miles away, I noticed there was a strange noise. At the time the engine was running at around 2200 rpm, and adjusting the throttle up or down between 1500 And 2500 seemed to make some difference but did not entirely stop the noise.
Referring back to this thread I looked for the you tube recording referred to in the initial posting, but while I didn't find it, I did find other "singing prop" recordings that sounded exactly like the noise experienced yesterday.
Running the engine while out of gear proved that the noise had something to do with the saildrive/prop system, and checking the oil level in the drive confirmed that it was not due to any shortage of lubricant. Eventually we raised the engine rpm to 2800, and while the noise did not entirely stop, it did reduce significantly.
With strong tidal flows along the route, some rocky shallows to avoid, and not knowing what exactly was the cause of the noise, it was with some relief when we eventually picked up our mooring.
I had not previously experienced the sound of a "singing propeller," though my colleague seemed fairly sure that this was the problem, but I think I will let the boat dry out against the dock wall, and get down and take a careful look at it just to be sure that all is well.

[Matay]

Sorry to comment without looking to the video but it was not availble I don't why.

I had strange experience that I would like to share.

One day I started to hear a strange noise after reaching specific rpm. But not in neutral.
I dive and checked everything was normal.
Until one day that I discovered the rubber diaphragm of the saildrive was loose at some points.
So when I had speed it was waving like a flag and when I was stopping for inspection it was taking the form it should be...

It is hard for to express the situation in English. I hope it helps.

[Salty]

Further to my posting No.14, above, I leaned my boat up against some timber piles last Saturday, and allowed the boat to dry out at low tide.
With the tide out I was able to examine the propeller. Firstly the prop turned easily by hand with nothing mechanically untoward being noticed, although earlier enroute to the drying out berth it was noted that the prop was still "singing."
Once the tide had receded it was noted that the paint coating was significantly damaged on the pressure side of one blade and with additional minor damage in corresponding positions on the other side of both blades (see photos below). This suggests to me that the prop had struck something underwater, though nothing had been seen, heard or felt at the time.
The decision had already been taken to remove the aluminium propeller, and to refit the folding bronze prop used last year.
During the return passage to our swinging mooring, we took a bit of time to give the bronze prop a bit of a twirl, and at the various revs tried, there was no repeat of any of the singing performance from before.