On Sat, 28 May 2005 20:47:10 GMT, "MarshallE"
wrote:

Hi,

I own a 1942 Wheeler (83 cutter from WWII) and am interested in learning
about prop design. My engines are 250 HP Cummings with Twin Disc Gears. My
goal is higher speed with lower fuel consumption without causing damage to
the drives. I know that the current props are 4 blade and generate 10 mph
at 12-1400 RPM depending on current and wind. My current fuel consumption
is 1.1 gallon per mile. The weight of the boat is 80 tons and is a
displacement hull.

Thanks for your help,

Marshall


Pitch:
a fixed pitch propellor has its pitch set to achieve an optimal angle
of attack at the desired shaft speed, and hull forward speed, both of
which contrl the value.

Diameter:
In general, a larger diameter leads to higher propuldsive efficiency,
until physical effects (like cavitation, or blade weakness) are
controling.

Projected area:
In general projected area is adjusted to absorb the available shaft
power at the desired shaft speed and target hull speed.

Can you say, "over-simplified?"

Hope this helps, all the same

Brian Whatcott