Prop splash

[Ivan Kozyakov]

Hi guys!


Sometimes I hear from experienced racers that the efficiency of a prop can be determined by the spray. Please explain how this works.
What should you pay attention to?

hq720.jpg

[Fluid]

The shape of the roostertail can tell a lot about prop performance. A low, flat ‘tail indicates a narrow, efficient thrust cone while a high one indicates a wide thrust cone. The latter is usually seen from high lift props used to raise the aft of the boat.



.

[vvviivvv]

Here is a comparisson of Abc vs Octura, not perfect as one is a 1.85m boat and the other 1.5m but you can really see how high the Octura throws the spray, the green one in sport setup is a 100mph boat.

Abc on my Hpr150


Octura X470 cut down on my Hpr185

[Ivan Kozyakov]

A little confused. Chopper prop shapes produce high splashes, while cleaver shapes props flatter, low sprays?
Does high splash always mean an ineffective propeller?

[dasboata]

Iv had my best speeds with gas cats & monos,,with big props run hi, on the transom , with a large spray , I run large pitch with much slip

[Gary]

Here is an old video where my boat was only running 92mph in this run but you can clearly see a pretty big water spray for that speed.
It is the same now as well but runs faster at 108 mph. I still feel a more narrow spray could give me more speed but need the transom way out of the water to prevent blow overs. Less spray more bite ???

https://www.youtube.com/watch?v=mvi9KIth-kg