And to add to the fire -- I tried an 4 blade 18pitch.
My goal is fuel consumption #1, #2 is getting & staying on plane at lower
speeds.

#2 was achieved, but 20 mph "on plane" with the 4 blade used more fuel than 30
mph wiht the 3blade. it also used the same amount of fuel at 20 mph with tabs
shoved all the way down -- so to me; the 4 blade was actually worse all around
than the 3 blade.

( I have a 4 blade 14.5x18 aluminum prop for sale with approximately 2 hours on
it if any one is interested-- I also have that 14x19 SS prop.... I'm keeping
the 15x17 and 14.5x19 prop for pulling & cruising)

I never understood why people are so adament about "aluminum flexes" .... it
just isn't logical to me.

-j


On Wed, 04 Jul 2007 09:04:26 -0400, trainfan1 wrote:

Steve Barker wrote:
You all can twist the facts all you want. Pitch is pitch.

No, it isn't. A thinner blade will travel further each revolution. A
fatter blade(aluminum) of the same will disrupt the water flow and not
travel as far.

In theory, a
given pitch goes xx inches through the water in one rotation.

Now you're mixing your "facts" with theory.

Given this,
the stainless and the alum will do the same inches in one revolution.

No, they won't. You're leaving out too many variables.

Until, that is, you put some power behind it and the aluminum flattens out a
bit.

No, it won't. The slippage you "see" is due to the blade cross-section
shape & design, not the blades flexing(until you get into composite
props). Props would be breaking all the time from fatigue alone if they
gave enough to even slightly affect pitch.

Thus the higher rpm for the same pitch.

The slippage you "see" is due to the blade cross-section shape & design,
not the blades flexing(until you get into composite props).

You can cup this and cup
that,

What about rake, leading edge & trailing edge designs, blade surface
area & thickness, diameter, blade contour & # of blades? Do you really
think pitch is all there is?

but the fact is the aluminum flexes and loses pitch. Period.

Prove it. What are your sources?


Rob