Thanks, it figures. I always knew Mr. King was no sailor.

CN


"Nav" wrote in message ...
Perhaps you did not realize that Doug is a just a motor boat driver now.
He has some sort of motor boat with nasty osmosis problems -he's
posted lots of pictures of it.

Cheers

Capt. Neal® wrote:

As a sailor you should be more concerned with trimming sails.

Leave the motors to the likes of Captains Shen and otn.

Captain Neal
(a member of an elite group)

"DSK" wrote in message ...

Farr1220 wrote:

Doug,

There's no need for the complication of variable pitch.

Well, sure. There's no "need" for the boat at all.


... A reversing
motor (electric or hydraulic) is all that is needed.

And that's simpler than a CPP?


... Hence for this
size vessel you see symmetric 4 blade props.

Sometimes 5 blade.


... The small increase in
efficiency gained by having variable pitch is not worth the extra
complication.

Bart wasn't asking about efficiency, he was asking about
controllability. An electric drive may be on par with the controlled
pitch for quick & easy reversing, but they're much less common... the
ones I know about have a bad reputation for being troublesome.

As for a hydraulic motor, if you think these are efficient and
trouble-free then I suggest you get some experience with them. It would
be at the bottom of my list for almost any power application.

Actually CPPs are slightly less efficient, ideally, than conventional
props becuase of the bulky hubs. However, in real world conditions, they
often achieve greater efficiency by being able to trim the prop to match
sea/wind conditions to engine load.

Fresh Breezes- Doug King