[Material for rudder stocks]

Delrin is a Dupont Trademarked engineering thermoplastic (it is a form of Acetal) used in precision parts requiring high stiffness, low friction, and excellent dimensional stability. I don't believe it contains any additional (IOM non-compliant) compounds to provide its strength and wear resistance. see https://www.dupont.com/brands/delrin.html

[The PRADA Cup - Challenger Series for the Americas Cup 2021]

I think that it was in the post race press conference about the on the water umpires had the necessary GPS enabled tools to decide on whether it was a penalty or not.  I would expect both Umpires (I think that there is an Umpire boat typically following each contender) to have communicated and both agreed prior to the "No Penalty" announcement being made.

[MPI S100-MG Winch]

It is available in the US from several places such as MPI https://www.maxxprod.com/mpi/mpi-15.html

Price is $130 plus shipping ($8).  You may well get charged import VAT duty and a PO handling fee (£8) that could well total about £30