Doug,

There's no need for the complication of variable pitch. A reversing
motor (electric or hydraulic) is all that is needed. Hence for this
size vessel you see symmetric 4 blade props. The small increase in
efficiency gained by having variable pitch is not worth the extra
complication.

Cheers


DSK wrote in message ...
Bart Senior wrote:
2 points

After hitting the lottery for big bucks, you have nearly completed
your 150' new sailing mega yacht. Included on your new toy are both a
bow and stern thrusters--for side-to-side control..

What sort of prop would you want if you were concerned about precise
speed control, and being able to back down nearly instantaneously?

Money is, of course not a concern.

Hydraulically controlled variable pitch.

BTW is this 150' yacht equipped with a rack of racing dinghies and a
retractable artificial beach?

Fresh Breezes- Doug King