Oil Seal vs conventional stern gland any experience out there?

[jfkal]

Previous owner fixed a Halyard seal. Since I had the boat I seem to have difficulties to get the shaft totally wobble free (high revs). I suspect that a conventional seal i.e. Volvo adds a bit of "grip" helping to tame the shaft. (BTW overall unsupported length is still within the specs but at the upper limit. Anyone who changed from conventional seal to drippless oil seal who experienced similar problems?

 

[Viking36]

Used the oil bath type seal for 8-9 years on previous yacht it was great. Dry bilge and no shaft "noise" transmitted. No shaft system totally vibration free. Suggest check prop balance,engine mounts and shaft alignment. Would never go back to conventional!

 

[nedmin]

Had Volvo seal on my previous boat for 10yrs with no probs. 4yrs on this boat. Used mainly in heavy silted waters. The main advantage is that the seal has its own built in cutlass bearing which always keeps the seal in line with the shaft.Grease it every year. You should not get a "wobble" on your shaft.

 

[andy_wilson]

They all wobble like mad!

The more flexible the seal, the less noise transmitted to the hull, and the better the engine mounts work.

 

[Colvic Watson]

I have a 'conventional' seal on my prop shaft and despite good maintenance we get an unacceptable amount of water in the bilge if we use the engine (definitely from the seal, not from skin fittings). How much do these non-drip seals cost and who supplies them?

 

[LeonF]

The Halyard is no longer manufactured. After the Volvo, which needs bleeding, the general consensus seems to be the PSS. Do a search, there had been a fair bit of posting in the past. Or talk to Volspec on the east coast. PSS is more than twice the cost of the Volvo.

 

[nedmin]

Only bleed mine when boat put in water after being ashore you just squeeze the rubber until water comes out. dont need to bother any more. Cost about £100 I have a raw water feed from engine just behind seal, this is probably because I have a long prop. shaft with an inner cutlass bearing, as well as one near prop. You need to talk with someone knowledgeable to see if you need this raw water feed.If your lucky Volvo might talk to you!!

 

[AndyL]

I fitted a Halyard seal after re-engining with a Yanmar 3GM. Never a moment's problem, one of the best peices of kit. Pity they stopped making it. I changed the cutless brg at the same time though. Yanmar's flex mounts are quite flexible and it worked just fine.

Perhaps you should check your cutless brg, or the alignment? Whatever type of seal, it is not actually supposed to support the shaft or prevent wobble.

 

[pvb]

Yes...

[ QUOTE ]
Anyone who changed from conventional seal to drippless oil seal who experienced similar problems?

[/ QUOTE ]
Yes, I changed a Volvo rubber seal for a Halyard seal. There's a bit more vibration with the Halyard seal - the Volvo rubber seal does have a substantial "cutless bearing" section inside it.

As I believe the Halyard seal is no longer supported, I guess I'll go back to a Volvo seal when the Halyard wears out.

Another factor worth mentioning is that the Halyard seal (and presumably other similar devices) makes it quite difficult to slide the propshaft back if you need to. I found this last year when I removed my gearbox.

 

[ex-Gladys]

Re: Yes...

One inch PSS was about £140 from ASAP when I last looked. Had one on Amber, never leaked a drop, but due to a host of muppet installation problems with the new engine installed by PO, it is being replaced with a Volvo because there isn't enough space.

 

[brianhumber]

Stern tube seals should not add support. Balance and alinment of shaft and prop are the deciding factors.
To give an example of this once in the Baltic the ice bent the tip of a prop by a few degees for less than a inch on a 9,000shp ship I was on. Resulting vibration and shaft movement meant power was restricted to less than three quarters full power untill this bent tip was shaved off.

Check your alinment and prop. If you use the seal to damp the vibrations you will shorten the life of the seal.

Brian

 

[brianhumber]

Re: Yes... Line shaft and seal support bearings

I would suggest the 'bearing' is to support the sealing lips not provide line shaft support - two different functions and design intent

Brian

 

[jerryat]

Hi jfkal,

Entirely agree with nedmin. The Volvo seal is superb, I just changed mine after 21 years without a single drop getting into the boat. The in-built 'cutless' bearing is there to ensure that the shaft stays exactly in line wit the seals whatever it does. It does not provide any support for the shaft.

Cheers Jerry

 

[pvb]

Maybe you should...

[ QUOTE ]
I would suggest the 'bearing' is to support the sealing lips not provide line shaft support - two different functions and design intent

[/ QUOTE ]
Maybe you should actually examine a Volvo seal in detail sometime.

 

[Birdseye]

[ QUOTE ]
Previous owner fixed a Halyard seal. Since I had the boat I seem to have difficulties to get the shaft totally wobble free (high revs). I suspect that a conventional seal i.e. Volvo adds a bit of "grip" helping to tame the shaft. (BTW overall unsupported length is still within the specs but at the upper limit. Anyone who changed from conventional seal to drippless oil seal who experienced similar problems?

[/ QUOTE ]

I certainly didnt experience the problem you describe and was entirely happy with the Halyard seal. If you are getting movement when you slowly rotate the shaft but not when the engine is running out of gear, then you have an alignment problem. You may even have a shaft straightness problem - something which is easier to sort out than you might think. When I had one, I gave the shaft to a man in my toolroom and he did no more than centre it, measure run out, and then leaned on the shaft in the right place and bingo - straight.

To be honest, I cant see a way in which a seal could cause wobble, and no seal I've seen in a boat is designed to act as a bearing and prevent movement. So I dont think its the seal. Try alignment first then shaft straightness - or thats what I would do.

 

[brianhumber]

Re: Maybe you should...

Well I freely admit the last time I had one apart was ten years ago when I fitted one to my fishing boat. The bearing on that one was fitted to support the seal lips and not the shaft in the hull opening, if the design has changed since then I apologise.
The Volvo shaft seal on Ronhilda is the original and over 16 years old with 4,000 hrs running so as others have said the design then was good one and externally at least they look the same design now.

Brian

 

[jerryat]

Re: Maybe you should...

Hi Brian,

Your 16 year old Volvo shaft seal is exactly the same as the current ones. As I noted earlier, I've just changed mine after 21 years only as part of her major refit. IMHO they are one of the very best value for money items on my boat. /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

Cheers Jerry

 

[jfkal]

Re: Maybe you should...

Thanks for all your opinions. Will revisit the alignmen then.