stern gland

[suse]

Searching for a stern gland that matched the diagrams in the books (note my extreme ignorance!), it was very worrying to find nothing relevant, and we had used the boat's engine for 150 hours with no stern gland maintenance. Subsequent admissions of ignorance to someone more knowledgeable produced what appears to be a sealed stern gland unit - apparently the original has been replaced with this maintenance-free option. Hooray! But hang on a tic - NOTHING is ever completely maintenance-free, is it?

The questions are - how does it work? When will we know when it needs replacing (ie before it seizes, not after)? Do we need to maintain it and how?

Thanks in advance.

suse

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[Gordonmc]

In all probability the stern gland, or cutless bearing, is made up of a rubbery phenol material encased in a bronze sleeve this drfts into a housing which screws onto the stern tube (or is mounted on a P bracket)
They work by simply supporting the prop shaft with cooling coming from sea-water which enters from the front down small holes in the housing. The water circulates down ridges cut into the phenol.
They don't need maintenance other than to make sure the water holes aren't gun ked up with anti-fouling or anything else. They do, however, wear eventually. Just look out for play in the shaft. It shouldn't have more than a couple of mm.

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[gtmoore]

If you mean at the end of the stern tube nearest the gearbox then this could be a Volvo rubber packing box. Does it look like this?

These need greasing once a year using a special grease available from Volvo (and you must 'burp' them when refloating after being ashore).



<hr width=100% size=1>Gavin

 

[snowleopard]

give us a clue..

there are lots of types.

the traditional one has a cap on top which you fill with grease & screw down a turn every so often.

there are some which have a bottle of oil connected by a tube, they feed a steady pressure of oil to overcome water pressure.

newer ones rely on two ceramic discs which are a very close fit, lubricated by a film of water - this is as near as you get to truly maintenance free.

there are also specialist types which rely on a car-style oil seal that you pack with grease (see previous posting).

the cutless bearing by the way doesn't provide a seal. it is a water lubricated bearing which needs no maintenence.

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[fjweaver]

the grease for the volvo type seal shown in the previous post is part number 828250 - a 27g tube. I bought some from RK Marine (Hamble) last week (£1.57+ Vat)

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[poggy]

Hi,

I have a Yanmar with a similar looking stern gland (how do you post photos), but it has two bolts which fit in a bronze fitting. I have a receipt for a re-pack last year. I just bought the boat and stuck it straight in the water, does it need "burping" and if so what do you do. It does squeel now and again at certain revs.

Thanks for your help.

Poggy

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[gtmoore]

The Volvo seal shown is quite simple with water lubrication at the back of the seal (grooved like the inside of a cutlass bearing) and grease at the front. The idea is that when you drop the boat back in the water you squeeze the rubber end to expel any air and allow the water into the gland. When water comes out then it's done. I've not heard it squeal - do you have a picture of it you could put on a web site and then post the URL? The rubber boot is marked Volvo.

Might be worth having someone who knows take a quick look mind as if it is the same kind and runs dry it apparently will damage the seal.

<hr width=100% size=1>Gavin