I came across the article at: https://e-surfer.com/en/questionable-patent-slowing-e-foil-trend/
A professor from the US filed 2013 (and got granted later) a patent for an electric hydrofoil although another professor from Sweden had already published similar work in 2009.
It seems that the patent was now licensed on an exclusive base to Liftfoils (maker of the eFoil) and that each professional electric hydrofoil maker has to acquire a license and needs to pay.
My thoughts / questions:
It feels for me that you can go against the patent in front of court, but how expensive would this be?
Is there a professional eFoil maker here, who has any experience how high the fees are?