Agree with JRD, I had a 36 foot heavy displacement boat
with a fair amount of windage, single screw. It was a handful
when docking in cross winds, many a time I wished I had twin
screws. Even in steel, converting to single screw sounds like
a massive project, new log shaft and rudder, possible re-configuration
of the keel, and what else?. In addition to the docking advantages
having two engines and charging systems would seem good to me.
The boat was designed for two engines, changing could possibly
upset the overall balance and performance? If you want different
engines for whatever reasons change them out. If it was my boat
I would stay with two engines.
Just my two cents worth, Dabnis