Leaky Stern gland

[Serendipity]

Hi All,

 

I'm hoping someone may be able to help me with my non conventional sealed unit which is very leaky (3 drips per second under way, although it settles down at rest).

 

Neither I nor the engineer at the marina knows what it is, and they won't touch it therefore, preferring complete replacement with a traditional unit.

 

If anyone knows what it is, and whether it is in fact serviceable, i'd be very grateful.

 

One pic below, and a link to another clearer though smaller image:-

 

http://i143.photobucket.com/albums/r150/ju...nd/DSCF0444.jpg

 

[Yamanx]

Thats exactly the same as the one I've just replaced.

 

I thought someone had effected a bodge repair on it when I first saw it, with the rubber hose and jubilee clips.

 

I cant ell you much about it because I cut through it with an angle grinder, prop shaft and all, burnt the rest out, through it in the skip and re-welded in a conventional type.

 

I do remember there was no apparent method of greasing and it didnt half bend about a lot when running.

 

Sorry I cant be much help.

[Serendipity]

it didnt half bend about a lot when running.

 

That's the same one then Yamanx! I too wondered if the pipe and clips were covering something else, but clearly part of the design then.

[John Orentas]

Looks a bit grimy !

 

Yes these things were common 15-20 years ago. They were an attempt at achieving a flexible stern tube which would allow a good deal of movement of the engine. The top brass element you can see is fixed into the hull in the same way as a more modern stern tube, the unit had a 'floating' bearing within it which would allow a lot of 'waggle' of the shaft.

 

The second lower unit is the stern tube proper and contains another bearing within which the shaft runs in a conventional way The two elements have castellated* ends to prevent the lower part from rotating with the shaft. The large diameter rubber tube connected the two parts together and forms a seal. Also on the lower component you can see a conventional 'stern gland' which should be used in the normal way.

 

It looks on the photo that the gland has run out of adjustment, at may well be it simply needs re-packing.

 

*There were some units that did not have the anti-rotation castellation's and relied on the rubber tube to stop the bearing twisting on the shaft. This type, if the shaft tightened in the bearing for some reason were known to get twisted up, tearing the rubber tube and allowing a lot of water into the boat with predictable results.

 

The things were generally OK and allowed the use of only one Hurth type coupling. Yours seems to have lasted. Possibly the rubber tube may need replacement and the gland re-packing.

[Serendipity]

Looks a bit grimy !

 

Thanks for the info John. If I could ever get it dry it would be a different story believe me!

 

Do you know where I could get instructions on how to dismantle and service it, and where I could get a replacement sleeve?

 

Also on the lower component you can see a conventional 'stern gland' which should be used in the normal way.

 

Wouldn't it have made more sense for this to be on the other end? Could I do it in the water on this unit do you think, or would it have to come out?

 

an attempt at achieving a flexible stern tube

 

Would it be wise to try and retain this feature, in your opinion?

[John Orentas]

Hi Serendipity.

 

I have just about exhausted my knowledge of the things, but I am sure it will come apart without much trouble, the main problem is that you would have to slide the propshaft rearward while you take things off.

 

Measure the dimensions of the rubber tube, it should not be too difficult to find a replacement, even a ring around some of the chandlers may be worthwhile and get new replacement jubilee clips (stainless). Check too re Yammy's point, is there a greaser fitted, it not it would not be a lot of trouble to drill and tap the unit and fit one, you will also need to measure the size of packing you will need.

 

Could you do the job while in the water assuming you have all the parts to hand ? Well two good acrobatic engineer/ fitters could tackle it. But I might decide to leave it for when the boat is next in dry-dock.

 

If you decide on a new stern tube and prop-shaft remember will need to think about extra flexible drive connections.

 

Might be an idea just to re-pack the gland for now and see how it goes.

 

Sorry to be a bit (or a lot) negative.

Edited October 30, 2006 by John Orentas