[hpv-boats] Folding Prop

[Rick Willoughby]

Dennis
My folding prop is slightly more efficient than the fixed blades I have.
http://www.rickwill.bigpondhosting.com/folding_prop.jpg

I have a prop optimising program that I use for prop design.  It is a  
bit more flexible than JavaProp and I can use a wide range of foil  
sections.

If you are interested in a design I can give you something that is  
reasonably easy to make using stainless flatbar.
rickwill at bigpond.net.au

It may sound odd but I have seen quite a few people mount blades  
backwards on boats.  They have the curved face facing aft.  This  
alters the effective pitch considerably from what is designed.


Rick
I checked out a rigid prop fitted to my small cat and was very  
surprised to find
that the speeds and the cadence were identical to my new boat fitted  
with the folding prop
It is quite difficult to get exact figures due to the river current  
which made a difference of 10%
based on 80 rpm.
It all ended with a bang when I hit something under water and bent  
one arm of the prop
back 40 mm.
I have concluded that my props are rubbish and I am going back to the  
beginning on the design.

Dennis


Rick Willoughby
rickwill at bigpond.net.au