T&T: Propellers

[Roger Bingham]

Extract from "Propeller Handbook" by David Gerr
Published by International Marine - ISBN: 978-0-07-138176-5
No connection

"How many blades?
Surprisingly the ideal is one.
A single blade does not have other blades disturbing the water flow ahead of
it. Unfortunately, trying to get a single-bladed propeller to balance is
like trying to clap with one hand.
Having two blades is the logical answer . . . . . . . .
The problem with two-bladed propellers for most vessels is that such
propellers require very large diameters to get the blade area required for
effective thrust.
As a result, three-bladed propellers have generally proven to be the best
compromise between balance, blade area and efficiency.
A four-blader, however, would seldom be as efficient as the three-blader
because the closer blades create additional turbulence, literally scrambling
up each other's water flow."

An excellent and very technical book which covers the subject in great
depth.

Regards

Roger Bingham
France