I enjoy making Power Functions-controlled boats to race (in water) in various LEGO convention competitions (which require 100% genuine LEGO pieces).
Usually, these boats end up being paddle boats, because of how inefficient all the LEGO propellers are. Supposedly Propeller 2 Blade Twisted (4745) is actually the most-efficiently shaped LEGO water propeller.
There are a number of problems with this propeller.
- The blade are thick.
- There is no good way to attack an axle to it.
- The shape of the blades is sub-optimal.
- It's on the small side.
Is there a way to build a more-efficient one, out of several pieces?