Rudder shaft - Grease or oil?

[Greg_Colleen]

Originally Posted by Wotname

Why??

The OP has some sort of composite bushing, probably acetal (Delrin) and currently the tiller steered rudder is out of the boat.

It should turn free and easy dry fitted on the hard when it is refitted and if it doesn't, the cause needs to found and addressed.

Once launched, the water is sufficient lubricant. There is no need for any other lubricant, Zerks etc (IMO).

EDIT - crossed posted with zstine .

Yes, I think you're right - I'm going with that.... much appreciated.

Please note; No more comments from grease and oil people.. thanks anyway

[Martkimwat]

If the shaft is binding, it could either be the shaft is bent OR, the previous owner replaced the bearings(s) and did not use the correct grade of Acetal which should be Delrin. Some people confuse the name Acetal, which is a generic name, with Delrin, but Delrin is a particular type of Acetal which is impervious to water, whereas most other Acetals will swell in water, which could cause the binding.

[Wotname]

Originally Posted by Martkimwat

If the shaft is binding, it could either be the shaft is bent OR, the previous owner replaced the bearings(s) and did not use the correct grade of Acetal which should be Delrin. Some people confuse the name Acetal, which is a generic name, with Delrin, but Delrin is a particular type of Acetal which is impervious to water, whereas most other Acetals will swell in water, which could cause the binding.

Hmm... AFAIK, there are only two types of acetal. A copolymer and a homopolymer. Delrin is the homopolymer type. The copolymer is better in water but both are suitable for rudder shaft bushes.

See https://www.lionep.com/uploads/files...-vs-Delrin.pdf

[Martkimwat]

Originally Posted by Wotname

Hmm... AFAIK, there are only two types of acetal. A copolymer and a homopolymer. Delrin is the homopolymer type. The copolymer is better in water but both are suitable for rudder shaft bushes.

See https://www.lionep.com/uploads/files...-vs-Delrin.pdf

I do not claim to be an expert so did not use unnecessary jargon, the less to confuse, however, the company I purchase my off cuts of Delrin from, are, (Ensinger Plastics, Waterlooville) and they are quite clear that Acetal is a general class of plastic that may not be particularly good in the marine environment as it may absorbs water and swells, except Delrin which does not. ie Delrin is a type of Acetal but Acetal is not necessarily Delrin. K.I.S.S.