Hello;


Any short explanation why prop cup start to work much better at speeds ower 40 mph?

Why do you think cup works better above 40 mph?

Brett

I do not know, I am hear this and do not understand why.

Actually cup is always working and effective to some point.
Boats become more efficient as they increase speed and rise in the water column. This may be why you heard cup is more effective at higher speeds.

Brett

Oh, just thought of a interesting example of a slow cup application We have put reverse cupping in local shore restoration barge propellers and it shows incredible thrust improvements and 5 and less mph in reverse!