How Does Propeller Size and Placement Affect Water Surface Speed?

[ahawes]

Water Propeller -- General physics questions

Howdy,

I have been following the boat bike concept for a few days and am interested in finding out more on how to get better water surface speed. The props on these bikes look small and the specs are touting no more than 10 km/h.

Can anyone point me in the right direction on where to get general information on boat props, screws, etc. How is the best performance obtained re: placement of the prop or screw in the water? Half in/ half out? Size of the prop in camber and diameter, pitch, etc? I am a pilot and understand a little on how to get more bite out of the air, and am wondering how this translates to the water world.


Thanks for any tips, web sites or information --

-- Andy

 

[russ_watters]

The key difference between a propeller on a boat and one on a plane is the density of the working fluid. Since water is so dense, you don't need to push as much volume to move a boat as you need to push air to move a plane.

The propeller must be completely submerged, otherwise forces will be unbalanced.