Manecraft Propeller Shaft Seals

[Nich39Nige]

Has anyone any experience of these shaft seals. I'm suffering from a leaky stern gland which seems to require repacking every season and am thinking of replacing it with one of these.

Nigel

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[Robin]

We inherited one (these are the Deep Sea Seals) on our current boat and replaced it with a new one since the survey found a small split in one hose. Since then we have had intermittent leaks from this seal and have had to adjust it for more pressure on the seal face than the instructions state (extra 7mm of movement). Previously it would leak momentarily each time forward gear was engaged and occasionally quite a bit on a very rough trip under sail when I think the engine moves on it's soft mounts enough to occasionally 'crack' open the face. Our engineer who installed it says it is very difficult to get the shaft mounted part at exactly 90 degs to the shaft, this may be our problem. We will be replacing ours this winter with the PSS seal which although similar seems to me to have a more positive shaft mounting part (S/S clamp with 2 non rotating O rings) and a more substantial corrugated hose that also provides the pressure on the face seal. There is a similar design one to the PSS called Stopelo in the French catalogues.

Also try a search for Deep Sea Seals here on the forums, they have come up before and there are some strong opinions expressed from one unhappy user!

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[Birdseye]

Must say I thought that these were the lip seal type seals as opposed to the deep sea ones.

Anyway, I have used both and would not hesitate to buy another lip seal type setup. These seals long ago replaced the old stuffing box type of approach in much of industry. They are very effective - no water leakage at all in my experience. And you can always replace them with spares purchased from an engineering supplies place (yellow pages) just make sure the springs are stainless.

Just dont see the point in putting up with the crudity and leakage of a stuffing box when there are excellent modern alternatives

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[Gunfleet]

Have you thought about the ptfe crumbly type gland packing they sell at West Marine? I've read good reports on that.

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[Robin]

I might be wrong but I'm sure (almost!) that the instruction leaflet says Manecraft though the seal was Deep Sea. If by the lip seal type you mean the one which was fed by a small oil reservoir to keep it under slight (oil) pressure, I think that one is no longer available though I believe it was very effective, just too expensive. If you know otherwise I would be interested as an option for us - certainly it is not in the latest ASAP Supplies book who used to sell it, and Halyard Marine said they no longer do it, too pricey.

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[30boat]

I've been using these seals(in two consecutive boats)for the last ten years or so, with no problems whatsoever.Quite probably the reason for this is that I have an aquadrive fitted so the shaft never moves forward or backward and the pressure on the mating surfaces is always constant.They're a little difficult to set up at first as they have to be square to the shaft but there's a way around that.Start by assembling the seal by following the instructions.Once the boat is back in the water and with the engine engaged at slow revs,check for leakage.If there is some,put the engine in neutral, slacken the jubilee clips(bellows side) enough to be able to jiggle the bellows sligthly, and try to square the bellows to the shaft by eye.Usually two or three attemps are enough.The compression will have to be monitored using the gauge provided all along.

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[Birdseye]

dont know who (if anyone) is selling the lip seal ones these days, but a member of my club has just made one himself, quite easily. requires access to a lathe to turn the brass sleeve in which the shaft runs and the seals fit. drilled and tapped for the spigot to the oil reservoir (use fully synthetic by the way since it does get hot).



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[MainlySteam]

There is a lip seal one made out here. It uses one lip seal only and is set up with a grease cup on the water side of the lip seal and they recommend running it with grease for the first 100 hours or so but then just letting it be water lubricated - but I think that is mainly for the bearing not the seal. It has a bearing inside to keep it centred on the shaft.

They are used in commercial vessels also which put up a lot of hours and seem to be very reliable - if they do leak you can stop it by packing it with grease via the grease cup (It works, I have done it). The manufacturer tells me that the main causes of failure are from damage to the lip seal when it is installed if the installer does not tape over the shaft keyway so the seal gets damaged (or occasionally they find the installer has put the lip seal in back to front!). There does not have to be a thrust bearing on the shaft to stop fore and aft movement.

John

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