What's the best (lower) rudder
bearing material to use?
We have spade rudders. The upper bearings are fine but the lower bearings are really too small, so we're increasing the shaft diameter (sleeving the shaft) & replacing the old (very worn) bottom bearing. The old bearings were self aligning (spherical, with a big hole for the rudder
shaft) but I see no point in that so we're going with a 4" high cylinder of bearing material around a 50mm dia shaft.
Primary Factors I'm looking at are: 1) Good wear resistance, & 2) Low moisture absorption.
Ultra-high Molecular Weight Polyethylene
(UHMW-PE) has excellent (almost zero) water
absorption & very good wear resistance, but low compressive strength & low PV-value (whatever that is - is it important?).
(?) and Polyacetate (+ glass fiber)
both have minimal water
absorption & much better compressive strength & PV but will glass wear my SS shaft?
Another option is Delrin
(Acetol or POM) which I know to be very strong but has ~12x higher water absorption.
Surely CF has several experts here? Thanks!