Stern Gland replacement

[SteveB_Sigma33]

I'm in the process of signing up for the new non toxic antifouling deal with boat scrubber (silicon painted bottom and then scrubbed as often as you want).

But before my boat has this done to it I'm going to change the Cutlass bearing and the stern gland.

Does anyone have any good recommendations for a make of stern gland? It's for a Sigma33 with a 1" prop shaft.

Any advice/recommendations?

Thanks

 

[Robin]

If you mean you want to fit one of the 'dry' shaft seals, IMO the best one is the PSS made in the USA but freely available over here.

See http://www.shaftseal.com/

I bought ours from http://www.lakesterngear.co.uk/ but ASAP also do them I believe.

There is a French one similar to the PSS and also the one called Deep Sea Seal, I personally think this is a poorly engineered one and removed the one fitted on my boat to replace it with the PSS. If you do a search you will find a lot of comments about Deep Sea Seals, rarely if ever complimentary.

 

[SteveB_Sigma33]

Looks good. Did you replace it yourself or get someone to fit it?

 

[RJD393]

The cheapest and probably easiest option is the Volvo Penta seal - it is a lip seal with no moving parts - works on the same principle as an oil seal. The only thing you have to do is make sure you expell the air on relaunch.

 

[LaurenceK]

Problem with the Volvo stern gland (whcih I think is the best thing available) is that it is only available in METRIC. No good for you.

I bought and fitted a Deep Sea Seal which partially failed halfway through a long passage and within three months of fitting it.

I now have a seal from AquaFax which looks fantastic. I fitted it myself (very easy) and so far, with very little use yet, it looks great. I think this may be the PSS seal referred to in one of the postings above.

 

[Robin]

I cheated and had the engineer at our club fit it as we were only out of the water for 4 weeks and pushed for time, but as long as you can separate the coupling from the shaft it is easy enough and you have to do that for all the types anyway.

 

[gtmoore]

I had a Volvo seal fitted 2 or 3 years ago to our boat which has an inch shaft and have had no problems so far. I did have to have a new bit made though. It's the part that screws onto the end of the stern tube - I'm not sure of the correct term for it.

It is a brilliant seal.

Gavin

 

[tugboat]

Robin & LaurenceK - I bought a boat last year which is fitted with a Deep Sea Seal. It performed fine on the delivery trip which involved a lot of motoring. The boat is in refit at the moment so ideal opportunity to change it, but I'm curious (having previously always had stuffing boxes) to know why they are considered to be poorly engineered and how the mentioned failure occurred. Several types, including the PSS use a bellows which seems to me to be the weakest link and where they are most likely to fail, so what makes the PSS more reliable? Glad to benefit from your experience.

 

[SteveB_Sigma33]

I'm pretty sure the seal I have on at the moment is a PSS type, but the collar grub nuts became loose and even though I used the correct sized allum key to try to undo them the became rounded so I had to drill them out.

The heath robinson fix was to use some of the super strength duct tape with two jubilee clips to make the collar turn with the shaft. Works great with no chaffing or ripping of the tape and saved me a lift after I had just gone back in.

Wondering if it's worth taking it off and just getting some new holes sunk in and taped with a thread?!?!

There is no leakage, but as I'm signing up for this silicon deal I don't need to be lifted apart from sac anode changes so I'm probably not going to have any long periods out of the water for the next 3 years.

 

[RJD393]

Although the VP seal is only available in metric sizes in practice the 25mm on will fit on a 1" shaft (25.4mm) I fitted one to my Moody several years ago with no problems.

 

[Steve_N]

Agreed - I've had 2 boats with 1" shafts both fitted with the metric Volvo seal (by their respective reputable builders) and both worked faultlessly.

 

[jerryat]

Yep! Agreed. The Volvo seal is excellent and WILL fit imperial equivalents. Beats me why people pay far more for fiddley, dripping alternatives. Just changed my VP seal after 20 totally drip free years - and then only because I'm doing a major refit!

 

[BrendanChandler]

[ QUOTE ]
The cheapest and probably easiest option is the Volvo Penta seal - it is a lip seal with no moving parts - works on the same principle as an oil seal. The only thing you have to do is make sure you expell the air on relaunch.

[/ QUOTE ]

I recently had one of these fitted when the previous rubber seak died of old age. It was fitted whilst afloat and seems to work well and is more substantial than the previous seal.

Brendan

 

[Robin]

Do a search on Deep Sea Seals there has been a lot said, some of it very harsh!

IMO the Deep Sea Seal has a smaller sealing area, weaker bellows (much) and the rotating part which clamps to the shaft is mounted in a bellows too and is very difficult to mount exactly at 90 degs to the shaft, even with the supplied template. If it is NOT at 90 degs the seal runs eccentrically and the seal width at it's smallest point may be VERY small, any futher movement such as engine movement on it's mounts could be too much. The PSS type have a rigid collar which slides over the shaft and seal to it by 2 O-rings (non-rotating so don't wear), this gives a true 90 deg fit to the shaft without any need for a template. The PSS bellows is a heavy corrugated type as opposed to the very soft Deep Sea Seal ones where there are actually 2 bellows to the PSS one. The seal width of the PSS is much wider and allows for more engine movement.

Our boat came with a Deep Sea Seal that I replaced because it had a split starting in one of the bellows (3 years old). The replacement occasionally leaked in heavy seas if the engine moved too much on it's mounts which are very soft (Yanmar). The PSS we had fitted last winter has not leaked a drop since and IMO is a much more robust piece of kit. We chose the 'high speed version' as recommended by the UK suppliers and PSS, this allows for water injection if required to cool the seal but in our case is used not for water injection but as a permanent air bleed. The waterfeed tube on ours is simply taken from the seal to a point above the heeled waterline so that a small head of water is maintained, it is not then necessary to 'burp' air from the seal after being out of the water and I believe it also stops any venturi effect 'sucking' water out of the stern tube at speed and maybe making the seal run dry and getting hot. I believe the UK importers may now only bring in this 'high speed' version, the only difference anyway is the provision for a small hose connection which adds a small amount to the overall length of the seal.

 

[Robin]

I don't think I would be very happy with Duck tape! You might be able to get a new collar perhaps from the makers as a replacement part or as you suggest have it drilled and tapped a size up if there is enough meat in the collar. I added a couple of jubilee clips on the shaft, with the screws 180 degs apart, as a back stop to prevent the collar moving and slackening the seal pressure should the clamp screws work loose, I did the same with the Deep Sea Seal which was only held onto the shaft otherwise by a jubilee clip clamped over the bellows, and the bellows on that was so soft it 'migrated' around the tightened up jubilee clip.

 

[Ben_e_Toe]

RJD393 mentioned the Volvo Penta gland and the need to 'expell air' from it on returning it to water.... Does that just apply to the first time or every time?

Also, whilst I'm on. Said gland is running fine no leaks etc, boat is 18 years old but one year old to me - should I 'service' the gland or just leave well alone and pray?

 

[tugboat]

Robin, many thanks for the detailed reply - much appreciated. I shall now look at my DSS with a more educated and critical eye and it would certainly seem prudent to make a change.

 

[john_morris_uk]

We fitted a PSS seal to our Sigma 33 and were very happy with it. In fact one of the first things we did on our Westerly was to fit a PSS seal. I have not had any problems with the Stainless Collar grubscrews coming undone.

 

[TheBoatman]

It's everytime that you re-launch the boat when the seal has been out of the water. All the time the boat is afloat you don't need to worry. You should squeeze the end until some water comes out, job done for the rest of the season.

 

[pgriffith]

I have a volvo stern gland ,it is dripping do i need to replace it ,do you know were i can get one ,in a rush ,in oz weather changeing have to get moving .