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[BarryM]

I thought this might get a few views if only from those asking "What's a Tribologist?" 

Aldi's offers for the 28th February include not only an attractively priced air compressor but also air compressor oil. Given that this must be suitable for high temperatures and miscible with water, would it be any good as a steam oil?  (Anything to avoid paying too much.)

Barry M

[Bunkerbarge]

A Triboligist is someone who studies the interaction of moving surfaces and associated coefficients of friction.

It is basically the study of lubricants etc..etc..  Did you know that you can use Tomato sauce as a lubricant?  Did you know that you can use water as a lubricant?  Did you know that you can use water as a lubricant for large cruise ship stern tube and "A" and "P" bracket bearings?

All interesting stuff.  As for compressor oil being used as steam oil, the viscosity of compressor oil is considerably lower than that of steam oil so I would say no.

[BarryM]

Water has been used for stern tube, A-frame and P-bkt bearings since Noah was a lad in all kinds of vessels; not just tourist barges. Just about anything will act as a lubricant if the conditions are right.

Cheers

Barry M

[Bunkerbarge]

I think that's the first time I've heard of a 83,000 ton cruise ship referred to as a "Tourist Barge" 

[Colin Bishop]

Apt though! 

[BarryM]

Sorry - Motorised Tourist Barge!

[Bunkerbarge]

It is interesting to know that the stern tube arrangements of cruise ships has turned full circle nowadays. 

Originally the Lignum Vitae lined stern tube was cooled and lubricated with sea water and proved to be a successfull arrangement for many years.  This was superceded by the oil filled white metal bearing type arrangement, which although a more efficient set up from a frictional arrangement has always been susceptable to environmental concerns, requires a seperate oil system and has to have two seals for every bearing in the line shaft.

Finally we are back to the latest arrangement which is once again water cooled and lubricated but the Lignum Vitae has been replaced by a synthetic bearing material known as an Elastomeric Polymer Alloy.  This is simply fed by an inboard sea water supply and requires only one seal for the entire line shaft.

[Colin Bishop]

That's interesting. Just shows how the various incremental improvements add up to more than the sum of the parts. Whilst I don't much like the look of modern cruise ships, I fully accept that from the engineering viewpoint they are in many respects much superior to previous vessels with the possible exception of seakeeping ability - but then they are not designed to take bad weather in their stride, the policy is to dodge it, for which I imagine the great majority of passengers are most grateful.