Shaft seals

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TEPER

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Hang on chaps this is a question not an instruction!!
I'm looking to fit a water lubricated shaft seal to my Moody 336. Has anyone done the same and can give advice on how to plumb in the water supply? Where taken from? Pipe run?
I'm confused as the whole engine cooling circuit appears to be below the waterline.
 
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Hang on chaps this is a question not an instruction!!
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Does the seal you're fitting need a water feed? I've fitted a PSS seal to my Moody 33 and it's just lubricated by the water in the bellows. You have to remember to 'burp' it when the boat's been out of the water. I also had a Deep Sea seal on a previous boat that had a feed from the sea water circuit but I seem to remember this was unnecessary at speeds below about 10 knots!
 
I fitted a PSS seal on my Moody 425. Ran a 3 foot length of pipe from the nipple up the side of the engine compartment and the head of liquid stays at sea level. Works fine.
 
Glad it's a question. The alternative sounds painful.

You don't say what type of seal, but I bought (from ASAP) and fitted a PSS seal 12 months ago. Can't remember the precise reason why, but the basic type of PSS seal that needs burping wasn't available then. Instead, there was a hose tail fitting on the seal. This is not for water lubrication directly, but simply to ensure that water can get into the seal, rather than being air-looked out should the boat dry out (hence the burping you've seen described for 'closed' seals). At the sort of shaft speeds and horsepower yachts produce, no forced water lubrication is required. It's a very simple matter of looping the tube a good height above the seal (into a locker, for instance). The PSS seal comes with clear insructions about what's needed. All you'll need is a couple of metres of hose and clips.

So far, incidentally, the PSS has worked supremely well. It leaks no water, shows no discernible wear and needs zero maintenance other than a periodic look-see.

Incidentally, if your "whole engine cooling circuit appears to be below the waterline" (as is mine), does it have an anti-siphon on the inlet side? It's good practice.
 
Volvo do one that's extremely simple, but effective. It's just a rubber cone that attaches to the inboard end of the stern tube. My last 3 boats have all had one as standard fitting.

Virtually no maintenance, apart from a small squirt of grease once a year (small tube of it provided with the unit), plus a 'burp' after each launch.

Part number: 828254 for 25mm shaft.
 
I would endorse the simplicity and relatively modest cost of the Volvo seal. After several recomendations I have just had one fitted to my M336. The engineer who fitted it said that the one on his own boat had proved to be extremely reliable over several years with minimal maintenance requirements.
 
Yep, totally agree with that. I've just changed our Volvo seal after 21 years with no prolems and only because I was taking the the shaft out as part of a major refit. Absolutely no water at all got past it in all those years.

For a Volvo bit of kit it is incredibly good value and totally reliable. I have never understood why people still mess around spending loads more money on other types that are very seldom as effective for so long a period.
 
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