Stern Glands

[Kato]

I have just bought a 1978 Moody 33 which has a "deep sea seal" stern gland, fitted about 4 years ago. At 1700 revs it leaks. At the top of the seal there is an air breather. I have discovered that the instructions for the current version show an air breather as well as a connection to the raw water inlet. Is it necessary to instal this on my "older" version? How does the water connection serve the seal? The new version is also distributed with warning notices to be posted for the crew as to how to tighten the collar around the static part of the seal in the event of its failure! One (reputable) engineer of whom I asked advice said emphatically that I should change the seal as soon as possible for the conventional type but with Teflon packing. Perhaps I am being fainthearted but I now feel uneasy about the efficacy and safety of the seal type gland. Does anyone have any views on the matter?

 

[cliff]

Change it at your first opportunity!
Either go for conventional greased stuffing type or oil filled triple seals.
I've read too many complaints concerning the deep sea seal type to even consider one on any boat I owned.
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"Artificial intelligence is no match for natural stupidity"

 

[Steve Clayton]

Kato,

Welcome to the world of Moody yachts. You will find lots of help, and friendly people, here
www.moodyowners.org.uk

Steve

 

[Robin]

Water injection is generally only required on high speed shafts but you need to release trapped air after drying out (winter ashore for example) so an automatic means of doing this via an air bleed taken above the waterline is convenient or you need to burp the gaiter by hand.

There is normally a little gauge supplied with the Deep Sea Seal to adust the gaiter pressure put on the seal, the adjustment may well have slipped which would cause your leak above 1700rpm. The grip of the Deep Sea gaiter is poor IMO and when I had one I backed it up by two jubilee clips clamped on the shaft behind it. It is important too that the face is at 90 degs to the shaft, difficult to achieve at arms stretch in a confined space but essential. The PSS seal uses a different seal to the shaft via a solid S/S collar held to the shaft by allen screws and sealed to it by two (non-rotating) O-rings, this is much easier to set up and adjust.

Personally I think the Deep Sea Seal is weakly constructed and many folks have reported problems (do a search of the forums). We inherited one with our current boat, there was a split in the gaiter starting and we replaced it but later changed the seal for the much better PSS seal which IMO is much more robust and gives a wider seal area more able to cope with even significant engine movement in a seaway (we have softish engine mounts). Our PSS is fitted with the water inlet connection but this is used to provide an air bleed only, with the tube connected to it taken up above the waterline, this was suggested after discussion with PSS.

I have to say I would stick with our PSS seal over the older packed stern glands which need regular greasing (and the grease eventually gets spattered around as the shaft rotates) as our PSS gives a totally dry and clean bilge. Conventional stern glands wear the shaft over time then leak, and are even meant to be adjusted to 'just' leak under way, whereas the dry seals will work with a shaft that is already worn.

Welcome to the forums BTW!

Robin

 

[jerryat]

Change to the Volvo shaft seal, then forget all the problems/leaks etc!!

Won't repeat details as there was a post here within the last week, and loads in the recent past.

Do a search and give them some consideration before deciding, I think you'll think again!

 

[dulcibella]

Halyard oil-sealed glands seem very trouble-free. I agree that the "deep sea seals" are accidents waiting to happen.

 

[Juggler7823]

Halyard no longer market this type of seal but say they they carry a small stock of spares