Capt J: What about Pulse surface drives? There's a 14m Pluckebaum with twin 575 gas motors - it'll do 50kts no problem.
Pulse isn't still in business are they? It will be interesting to see if Capt J has run across any as I never have.
Apparently they were bought in 2006 by Ocean Technologies. https://boatingindustry.com/news/2006/03/28/ocean-technologies-acquires-psi-surface-drives/ By in 2010 were gone again. I answered my own question. Here's a list of current drives https://www.boatdesign.net/Directory/Propulsion/Drives/page2.htm