Hey all, I have been working slowly in the background on the design of a long endurance ocean going vessel. I have it all pretty much together other than how you achieve your wet interfaces.
My experience is that, even if you use a strong copper antifouling, rudder shafts and propulsion shafts start to gum up with sea life.
I have looked at stuffing boxes, magnetic couplings grease feed systems, etc.
Stainless rudder shafts in brass tubes with a large clearance appear to be the best bet so far for steering. The servo can be inside a waterproof enclosure with a rubber boot around the connection rod.
I still haven’t found an answer for propulsion. Even if you use a magnetic coupling to keep water out, the coupling to the propellor still runs through bearings. Again, stainless in brass with clearance can work as it is low RPM.
So, has anyone else got ideas on 1. How to keep the water out. 2. How t stop them clogging up with marine growth.