Rudder bearing material

[Budgerboy]

Morning all
I'm in Agious Nikolous Crete dropping my rudder and pulling out prop shaft to change the cutlass bearing..Rudder is skeg supported and I will need a new lower bearing. Local guy says he can get one machined up (fairly simple job ) out of Teflon..Not sure this will be ok.. Don't think I could source Acetal locally here..What do you think? Boat is a Barbican 33.
Paul ?

 

[coopec]

Plastics absorb water to a limited degree. ... The only polymer with zero water absorption is PTFE. Plastics with very low water absorption are polymers such as PEEK,PPS, PSU, PPSU, PEI, PVDF, PET, PPE, PP and PE. Furthermore, low water absorption is exhibited by POM, PA12, PC and ABS.
Dimensionally stable plastics | Ensinger

TEFLON TYPICAL PROPERTIES of PTFE - Catalog
Water Absorption, 24 hrs (%). < 0.01. 0.02. 0.05. MECHANICAL. D638. Tensile Strength (psi). 3,900. 2,100. 1,900. D638. Tensile Modulus (psi).
https://catalog.wshampshire.com/asset/psg_teflon_ptfe.pdf

 

[Budgerboy]

Thanks..So is Teflon PTFE?
Paul

 

[Budgerboy]

Looks like Teflon will be ok?

 

[LoneHort]

Hi there is a product called Vesconite , see here,

Vesconite Hilube - Vesconite

They have recently added common sizes in stock in Europe and if you reach out to rosa at vesconite.com she will supply you with what you need. She gave me a price for my cutlass bearing that was similiar to the equivilant in metal.

Hope this helps,
Micheal

 

[vyv_cox]

The problem with using PTFE is that its mechanical strength is achieved by filling with powdered glass. Raw PTFE is clear with poor mechanical properties. Stainless steel can be badly worn by rubbing contact with PTFE.

I would be very surprised if acetal was not available in Greece. As posted above, Vesconite is excellent but not cheap.

 

[andsarkit]

You could try sourcing Delrin which is a variant of acetal and may be better for your application.

 

[Praxinoscope]

Delrin/Acetal should do the job perfectly, about 15 years ago a friend had a problem with the rudder bearing on a Centaur, we replaced it with a Delrin bearing which is still working well.
Delrin is a trade mark of Du Pont Chemicals, there are probably alternative trade names for acetal.

 

[Rhylsailer99]

The problem with using PTFE is that its mechanical strength is achieved by filling with powdered glass. Raw PTFE is clear with poor mechanical properties. Stainless steel can be badly worn by rubbing contact with PTFE.

I would be very surprised if acetal was not available in Greece. As posted above, Vesconite is excellent but not cheap.

i Make bait pumps and tried a ptfe bush once and it wears super fast, uhwmpe ive found the beast for wear.

 

[coopec]

i Make bait pumps and tried a ptfe bush once and it wears super fast, uhwmpe ive found the beast for wear.

Did you mean uhmwpe live found the best for wear?

 

[Rhylsailer99]

Did you mean uhmwpe live found the best for wear?

Yes I always mix the h and m up