A bit more information, the noise starts just above idle, and goes away at 1400 rpm.

Morningbird, good idea to call the distributor and I will do that. I had thought about wear but the noise started immediately after the anti foul so that seems like a bit of a coincidence.

Ramona,


No, the instructions are very specific stating that oil, grease, silicon are not to be applied to the seal. They also state that a squeal can mean there is no water, but I had checked that by burping the seal, and checking that the bleed line is clear.

web site for PSS is here. http://www.shaftseal.com/en/product_categories.

Jolene,

thanks for the feedback, it is interesting that you do not have the problem. I do not have time to work on the boat for a couple of weeks but am planning to talk to the supplier, check the breather / vent line then if the problem persists check the preload.

That is exactly right Cisco, doubled up grub screws, a real trap, especially if you didn't fit the seal yourself. Also the collar /seal face can be reversed if you have corrosion pitting in it.
I run raw water from the engine cooling pump through the seal so it exits out the cutlass bearing aswell, this helps with removing air and lubrication.

l have them on a 30 ft mariner flybridge cruiser ( l know, l know...not a yacht LOL ) with twin 315 hp mercruisers,
the problem l have is the starboard grub screws vibrate loose for some reason after leaving the mooring and spray sw over the transmission and rear of the recently replaced donk,
each time we go out l adjust the flange and tighten the screws, only for it to happen again, which also sprays water on some sensors which causes the donk to surge and alarms to go off,
only does it at the the start of the day, works fine after that...until we go out again

Bayview,
Like Cisco said there are two grubs in each locking thread, if you are not removing the top one and tightening the one in contact with the shaft you will never get it tight. Locking grub screws like this( one on top of each other) is a real trap, I have come across it before on other equipment and usually there has been damage done because somebody was unaware of the locking method. You may be aware of this Bayview, it is just fairly uncommon. Check the shaft for excessive end float and that the shaft is tight in the gearbox coupling too.

Jolene said..
That is exactly right Cisco, doubled up grub screws, a real trap, especially if you didn't fit the seal yourself. Also the collar /seal face can be reversed if you have corrosion pitting in it.
I run raw water from the engine cooling pump through the seal so it exits out the cutlass bearing aswell, this helps with removing air and lubrication.

Jolene,

the water line to the seal is interesting, mine is set up as a vent only. Is the line to the raw water line connected to the suction or discharge side of the pump?

Do you allow your prop to free wheel when sailing? I do, and the spinning prop can generate the noise under sail, but only at speeds around 6.5 knots.

cisco said..

LMY said..

Do you allow your prop to free wheel when sailing? I do, and the spinning prop can generate the noise under sail, but only at speeds around 6.5 knots.

Allowing your prop to spin while sailing is like putting a speed governor on your sailing performance. Also it can cause excessive wear in your gearbox or even ruin it if your gearbox depends on forced (pumped) lubrication from the input side of the mechanism.

It also causes excessive wear in your stern gland, stern bearing and P bracket bearing.

If you have a mechanical clutch as opposed to a hydraulic clutch, the shaft can be locked by simply having it in gear when sailing. I usually put mine into reverse. Don't worry. It will not involuntarily start your engine.

A locked propellor causes less drag than a free wheeling one.

I thought that I read that Yanmar recommends that the gearbox is left in neutral while sailing but I could be wrong

Here it is

www.catamaransite.com/files/YANMAR_MSA08-003_Neutral_Sailing.pdf

Regards Don

LMY said..
Jolene,

the water line to the seal is interesting, mine is set up as a vent only. Is the line to the raw water line connected to the suction or discharge side of the pump?

Do you allow your prop to free wheel when sailing? I do, and the spinning prop can generate the noise under sail, but only at speeds around 6.5 knots.

The water passes through the seal from the engine output/discharge. Water travels through the engines heat exchanger, exits the motor, travels up through an anti-siphon loop (above the seawater level) then down to a T where most of the flow continues to the exhaust elbow, a small line from the T takes some flow to the seal and exits out the cutlass.
I have a feathering prop that stops the shaft from turning whilst sailing. Because my gearbox allows the shaft to free wheel in the direction of drive, I need to select reverse to lock the shaft from being able to spin in the forward drive rotation so that the prop will feather. Alternatively I can grab the propshaft with my hand, stop its free wheeling rotation and the prop will feather.
A good example of the drag created by a spinning propeller is a helicopter. If a helicopter has an engine failure and the rotors can still spin, the pilot can lower the collective to keep the rotors spinning from the air rushing through them, "Autorotation". The drag from the spinning rotors can reduce his decent rate and give him a chance of landing or crashing with style.
However! if the rotors stop spinning, the pilot returns to earth at 32' second/second for a catastrophic landing.

And a interesting article with test data www.catamaransite.com/propeller_drag_test.html that comes to the conclusion that a stationary 3 blade tested had 3 times the drag of the same prop allowed to rotate

Regards Don

Hi Cisco

On mine I let it freewheel but the previous owner who used to race it a lot replaced the original 3 blade with a 2 blade and marked the shaft so he could line it up behind the skeg and lock it in position

Regards Don

i would have thought that a feathering prop would most definitely have to be in gear when sailing , to flatten the blades out .

and a folding prop likewise to allow the blades to fold back , and not spin and open .


??????????????????

I have to use either my hand or the gear box in reverse to stop the shaft rotating to feather the prop. Once the prop is feathered it doesn't matter if the gear box is in gear or neutral as it ain't turning. If I select reverse to do the job, I can then go back to neutral and take a peek at the shaft to check the prop has feathered.



That's very smart !!!!!

What are the variables??

1. Folding/feathering props.

(a) Folding/feathering props:- Need to stop shaft for blades to fold/feather.

(I) Will sudden stopping of shaft by putting in gear damage clutch when shaft is spinning at hull speed???

2. Fixed prop.

(a)Test indicates three blade prop freewheeling causes less drag.

(I) A freewheeling prop WILL cause wear to P bracket and stern bearings as well as the stern gland and output shaft bearings in gearbox.

(II) Possible further damage to gearbox with hydraulic clutch which dictates having a separate prop shaft lock.

(b) A mechanical clutch locked shaft.

(I) How can damage happen to gearbox if nothing is turning??

(II) Possible Yanmar and Volvo recommend freewheeling shaft so as to sell more gearboxes/parts when you have worn gearbox out with all the sailing you do????


I think the Jury is still out.