Capt. Neal® wrote:


I think they are talking of a big catamaran which makes
it an entirely different animal. Little or no heeling and the
ability to travel at high speeds. Nice little transoms
available for twin tunnel drives. The ability to raise
the drives for beaching without fear of damaging the
props. Seems ideal to me. More efficiency in reverse
because of the tunnels which was the original desired
trait.

It looks to me, though, that a Kort nozzle would be
more efficient in reverse because of the more symmetrical
shape of the prop blades.

CN

It's a "general" rule that boats with Korts tend to lose some backing
efficiency over their un-Korted brothers .....couldn't explain why
(whether it's the shape of the nozzle or design of the prop, or both)

otn