"Jeff" wrote in message
. ..
Thom Stewart wrote:
Oh Boy,
a lot of double talk, off topic rambling, lord knows what amount of
nonsense theory and yet no explanation of why a 2 blade propeller is
useless.

I have two folding props and for ordinary weekend warrior heavy weather
there is no problem. However, in situations where the boat can surf down
large seas and achieve speeds greatly in excess of the intended prop
range, the water pressure will try to close the props. However, in these
cases you ordinarily would not be relying on the engines. I've had it
happen on two occasions, once when crossing Lake Ontario with the mast
down - it was downwind with 8-10 short chop behind us and we were surfing
up to 13+ knots. The other was also a following sea - 8-10 foot swells on
the beam with with 6 foot chop from the 25+ wind on the stern. I ran the
engines to make it easier to control while reefing (my crew was quite
under the weather at this point) and again found that surfing would make
the props act funny.

In cases where we've had to power against large waves, we don't achieve
the speeds that would cause this problem.



I don't know why a 4 blade fixed is a better propeller for a sail boat
(S) Guess I never will (g)

I thought this was a quiz. Why are you asserting that a 4 blade is
"better"? BC was just trolling with his post - he really has no idea.


Don't four blades have a greater Diameter Area Ratio than 2 or 3 blade
props. Doesn't the greater DAR give greater thrust?