stern gland system??

G

gd7hej

Member
Joined
11 Jan 2002
Messages
38
Location
isle of man
Visit site
hi, i have a trapper t28 built in 1968,she has been fitted with a 1gm but i need some information about the stern gland??the propeller shaft goes into a rubber gaitor with 3 jublie clips over the gaitor,there is a remote stuffing box goes down a pipe and i think this goes into the gaitor,i cannot find a locking nut?i get quite a severe water leak when motoring,then when stopped leaks quite bad till i pump grease into it,any ideas ie how to pack??or what...best regards graham crusha@manx.net
 
Hi
I had a boat that had a simple greaser as a shaft seal and like yours it leaked badly.I dumped it and fitted a deep sea seal instead wich gave no problems for the five years that I kept the boat.
If your seal doesn't have a locking nut it is probably a greaser type and not really suitable.
 
I have a similar system but my seal is fed from an oil tank situated just above the water line.The shaft goes through a bronze tube with two oil seals and the rubber gaitor is jubilee clipped between this bronze tube and the stern tube.
 
PSS seals are great - unless they fail, in which case water can come in VERY quickly. I know of one case where an engine mounting broke and the seal failed, resulting in a hurried tow in by the lifeboat of a vessel rapidly filling with water.

I now have mixed feelings about them - I'm sure a stuffing box wouldn't have produced the same dramatic leak in the same circumstances.

- Nick

bluemoment.gif
 
Nick

I looked at this and felt that I could easily apply a torniquet (sp?) onto the shaft/bellows if it did ever fail in service. Also that the SS rotor would prevent the shaft dropping out through the log in the worst scenario. Otherwise can't see that a stuffing box would have helped if a mount broke as the stuffing would be severely distorted. Do you have any more detail of what happened?

Tom
 
That can be scary.In my boat I have a Deep Sea Seal .There is also an Aquadrive that will keep the propshaft in place in case any of the engine mounts ever let go.I think that with a setup like mine face seals can be considered safe.
 
It was in either PBO or YM this year - as usual I can't find the article now I want to look it up . . .

I have sailed the boat involved, but wasn't there on that occasion and can't offer any more details. All I know is a high volume pump was required to keep the vessel afloat. I suspect that the people on board did not realise immediately where the water was coming from or what had happened. Once the water is over the seal putting a tourniquet on it might have been difficult. I don't think such a bad leak would have developed with a stuffing box, but I'm not sure.

30boat says he has an Aquadrive which would keep the shaft in place - would the Aquadrive coupling absorb enough movement if a mounting broke, or does he meant that using Aquadrive's soft mounts ensures that this can't happen? I have no idea, but am interested. Has anyone else had an engine mounting break, and what were the consequences? Are Aquadrives easy to fit, and how much do they cost? (I couldn't find prices on the manufacturer's website - usually a sign that something costs a small fortune). Are they worth fitting for the average (25-35ft) yacht with a 10 - 20HP auxiliary?

<font color=blue>Nick</font color=blue>
<A target="_blank" HREF=http://www.bluemoment.com>
bluemoment.gif
</A>
 
The present deep sea seal has a third hose clip with a wing nut and a retaining clip. Its purpose is to seal the shaft in the event of a catastrophic failure.
I have fitted four without any problems on different craft.

Iain
 
maybe I'm just lucky but I have an old fashioned shaft running through a tube with a packed gland on each end and a remote greaser for each end. Other than giving each greaser a quarter of a turn whenever I remember, I've never done anything else to it and it has never leaked a drop! I strongly suspect the entire stern tube is full of grease mind!
 
Aquadrive

Hijacking the post to some extent, sorry. However, in the spirit of the original post, I have a traditional stern gland with a greaser. I have experienced no problems with it in eight or so years and see little point in changing it to something that costs a lot and that increases the risk of taking in considerable amounts of water if things go wrong.

I paid 728 Euros in Holland for my Aquadrive, the smallest unit, the 20,000. It would have been significantly more in UK. My engine is a Yanmar GM30 driving via a 1-inch shaft. It was fairly straightforward to fit, if a little tedious, but it does involve making up a thrust plate and fibre-glassing that in place. I had my plate made in 6 mm steel after making a pattern in about half inch ply. If only I had a website I could show all the photos ;~)

Aquadrive is a constant velocity joint with the bearing housing attached to a thrust plate via a couple of rubber blocks. This is pretty rigid and not intended to be flexible, only to absorb vibrations that would be transmitted into the hull. The shaft is thus vitually locked to its position centrally within the stern tube. On the drive side the engine can be almost anywhere within very wide limits, something like 8 degrees. A mounting could break without it having the slightest effect on the drive.

My experience is that I would not fit one unless there was a very good reason for it. In my case it was because the very flexible mountings of the Yanmar allowed the shaft to contact the stern tube. Despite what Halyard claim the general noise level is now much higher than it was previously, except when the shaft knocked on the tube in a fairly limited rev range. I have spent a lot of time and money in ensuring everything to be perfect, e.g. new cutless bearing, checked shaft straightness, checked prop, checked P-bracket, but nothing has made much difference. Aquadrive is a last resort, IMHO.
 
Re: Aquadrive

I am sorry to disapoint you but my Aquadrive 20 000 cost me 499 Euros( approx. 313£) from ASAP last July.They gave me a 15%discount.
 
I think that the aquadrive would be strong enough to keep the engine more or less in place in the event of one of the mounts breaking.This would be unlikely to happen however, because the aquadrive takes all the thrust from the prop and the mounts only have to deal with the weight of the engine and its vibrations.The thrust plate must be strongly made and equally strongly bonded to the hull.Mine is marine plywood encased in fiberglass/epoxy.
In my case installing the thing wasn't difficult but it took a lot of work.
Ask ASAP for a catalogue, they have aquadrives and also centaflex couplings.
 
Re: Aquadrive

OK, perhaps I should have said cheaper than Halyard. I didn't try Asap but it seems that Aquadrive policy is fairly strict so far as exporting is concerned - Halyard refused to sell me one in Holland and the manufacturers in Sweden(?) wouldn't either. I had a quote from Spain that was more than Halyard or my Dutch supplier.
 
Sent an email to PSS and received the following reply, though it may pose more questions than it answers, eg how would you pull the bellows forward and what happens when you let go!:

Hi Tom,

Thank you for the e-mail regarding our PSS Shaft Seal.

If the engine shifted foreword, due to the mounts breaking, it could
separate the carbon and stainless steel faces. You could pull (extend) the
bellow until the carbon comes in contact with the stainless steel collar and
the water would stop.

You could also, as you pointed out, fit a clamp around the rubber bellow to
limit the water flow. Before fitting a clamp around the bellow, I would
first wrap a rag around the bellow.

I am out of the office next week at a Work Boat show in New Orleans. If you
have any other questions, I will reply when I get back. Also, feel free to
call me at: 800-523-7558.

Best Regards,

Dan Schalk
 
You must log in or register to reply here.

Share this page

Top