Paddle vs Propeller

My good friend John Iwerks animator, inherited his talents from his grand father UB Iwerks of Walt Disney fame. I got to talking to him about Force Fins and shortly after he drew out
my concept that we had been talking about. This was back in 1981.
I was trying to simply point out how my Force Fin worked like a propeller instead of a Mississippi paddle wheel steamer.
Paddle Fins are Terrestic Fins. The mass merchant split fins are nothing more than double paddles.