Stern Tube grease

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We had a discussion recently on another thread about removing stern gland packing and we drifted into talking about graphite-loaded packing, graphite grease (corrosion issues) and other suitable stern tube greases.

Things are nowhere near as obvious as you might think. I have today dug out two tubs of grease from my locker, both supposedly 'waterproof'.....

1. Castrol (Australia) 'Boating Grease' for 'Boats and Trailers' and 'Bearings, Rollers and Winches'. It says that it is a 'specially formulated adhesive lithium complex based grease suited to boating applications. It is water resistant and contains a powerful corrosion inhibitor to protect lubricated machinery parts. It uses a unique combination of anti-wear agents.......blah, blah,......NOT RECOMMENDED FOR CONTINOUS UNDERWATER APPLICATIONS (my capitals).

2. Morris K99 Water Resistant Grease. High quality lead-free calcium hydroxide sterate grease with special additives to provide extreme pressure properties, improve oxidation resistance and protect against rust and corrosion. RECOMMENDED FOR GREASE FILLED STERN TUBES OPERATED IN SALT OF FRESH WATER (my caps)

Several times I have been offered boating grease by chandlers for stern tube applications. It seems that one needs to check the tin for the specific words -- stern tubes.

Can anyone tell us what happens if you use the wrong grease?
 
I have little specialist knowledge on greases but it is my understanding that calcium stearate soaps are less water resistant than lithiums. So I'm not quite sure how your Morris K99 product can claim to be more water resistant?

Be that is it may, I have always used lithium soap greases for underwater applications, including stern gland, when I had one, and Blake seacocks, and any engine applications as necessary, such as the gasket on raw water pump. My stern gland did 12 years in my ownership and never leaked, never repacked. I have also repacked a good number of boat trailer wheel bearings with similar stuff, which all seem to have survived.

In the back of my mind is some info from my lubs research days, concerning greased ball bearings run in water. IIRC lithium lasted very well and surprised the engineers doing the work.
 
Can anyone tell us what happens if you use the wrong grease?

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It depends in which way it is wrong but the worst case scenario is that it will emulsify in a a creamy white gunge where it is in contact with water and offer limited lubrication qualities.

All the major companies make suitable greases for their marine divisions where they are used in pump glands etc however it seems they don t package in small quantities as much for our market as they used to.

There are a few Independant lubrication companies who try to fill the gap as per the tin of shaft greae you have and these often come to light if you google .

Many of THE WRONG greases will operate satisfactorily in the short term however you will see signs that they are not happy by the light colour of the grease that oozes up the shaft.

It is difficult to recommend an actual grade as every time I go to get a tin my friends Castrol seem to have come up with a new name for the recipe so heaven knows what they are offering today.

The two grades you have seem to have been formulated for two basic requirements.

1) This is a ball bearing grease which has been given limited anti emulsifying properties .

2) This may have lower load bearing abilities but has greater anti emulsifying properties.

There will of course be many other differences depending on what other additives have been used in each product.
 
I have just been snooping round with the help of Google and yes Vyv it seems the true waterproof greases are calcium based and there is one product that appears in Unipartmarine and Marine scene tins which would appear to be the same formula as the suitable uses are word for word identical.

Shaft grease


I like you have used lithium grease as well with no real ill effects and ony very slight signs of emulsification so there is opbviously a certain amount of latitude. We would often use lithium greases on pump gland greasers on both fresh and sea water pumps on ships with no ill effects. In fact there were very few applications where we used a "water proof grease".

Unfortunately some calcium based greases are creamy white so give the false impression of emulsification.

For the purists it seems there should be a product in your chandler sold as Waterproof Grease such as by Unipart Marine.
 
[ QUOTE ]
... it seems the true waterproof greases are calcium based and there is one product that appears in Unipartmarine and Marine scene tins which would appear to be the same formula as the suitable uses are word for word identical.

For the purists it seems there should be a product in your chandler sold as Waterproof Grease such as by Unipart Marine.

[/ QUOTE ]Doesn't it look more like the Castrol product that says it is unsuitable for continous immersion? I have tried to get more information on the product via Google and the various Unipart sites but can't find any.

Googling, I came across a July 2007 ybw thread on this very subject -- I would have missed it at the time as we were cruising without Internet.....

http://www.ybw.com/forums/showflat.php?Cat=&Board=pbo&Number=1515684

I think that the Morris product is widely available in the UK chandleries - I think I saw a poster mention it on YBW the other day. Mine has a Peters (Chichester) price tag on it but I think that Aladdin sold it too? The only product that I have found to be marked for stern tubes on the tin is the Morris one, though see the thread above.

It seems that some chandleries are very sloppy and I know one marine engineer who is clearly not bothered by the type of grease to use, which is disappointing as he is in other respects an excellent mechanic.
 
most waterproof grease I ever came across was that zinc containing stuff you slapped on the kids arses to prevent nappy rash
 
Can someone explain how a gland that is dripping is completely immersed ? One end of it may be ... but rest is subjected to a thin film of water as shaft takes it round.

Boat Trailer wheel bearing grease has been recc'd for years and sorted out thousands of boats - without trouble.

Guy before me was using std Castrol high point grease in it ...... I have to admit I used it till pot ran out. Biggest difference I found when I changed to normal recc'd trailer bearing grease - less grease flung around bilge by the excess coming of shaft.
 
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Can someone explain how a gland that is dripping is completely immersed ? One end of it may be ... but rest is subjected to a thin film of water as shaft takes it round.


[/ QUOTE ]If the gland is dripping then there must be a passage for water to flow, right through the grease 'channel' and the motion of the shaft must presumably cause surface action? I would have thought that at the surface you had quite a lot of movement?
 
[ QUOTE ]
[ QUOTE ]
Can someone explain how a gland that is dripping is completely immersed ? One end of it may be ... but rest is subjected to a thin film of water as shaft takes it round.


[/ QUOTE ]If the gland is dripping then there must be a passage for water to flow, right through the grease 'channel' and the motion of the shaft must presumably cause surface action? I would have thought that at the surface you had quite a lot of movement?

[/ QUOTE ]

Agreed about water passage but I wouldn't call it "immersed" ... it's certainly wet and good job to or you have a over-tight gland. And 'movement' what movement ? Of shaft ?
 
Doesn't it look more like the Castrol product that says it is unsuitable for continous immersion? I have tried to get more information on the product via Google and the various Unipart sites but can't find any
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It seems that Castrol do lithium products which are suitable for some uses where water is present but have good load bearing properties for ball bearings etc hence being described as suitable for bearings in launching trailers. Ie they might get wet but don t run consistently in water.

For duties where water is present then Castrol do a product Castrol WR Grease...I had a look in Halfords today when out stocking up the Bosuns store and found that neither Halfords or local chandlers stocked this product so may have to search..However it is not beyond the bounds of possibilty that the Marine scene and Unipart marine is Castrol...I might have a word with them in Swindon next week.

Castrol WR is a calcium(lime) based light coloured lubricant and is similar to Castrol PH however the latter may have slightly different properties as it is sold for things like door catches and bonnet catches on older cars. Halfords have this but in a designer aerodsol bottle.

As I said in an earlier post I have often used lithium type greases on stern tubes and sea water pump bearings and not encountered any problems.

These matters are detailed in the Product Sheets

What you should be looking for is a calcium based product.
 
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