getting prop cupped
 

I have a set of 25 mirages that I think cupping will help my slipping proplem, If I get them cupped would that make a pair of mirage plus's ? Dwight

No, it will make a pair of Mirage's with added cup.:D :D

Will probably be about the same as Mirage Plus's though.

ok I guess I deserved that answer, I asked the question incorrectly:D :D Dwight

Hi Whitey,

Adding standard cup should reduce slip. However, it is the equivalent of adding about 2 inches of pitch which will reduce your RPM by 300 to 400 RPM. Are you currently running at the top of your chosen RPM range. If not, adding cup may in fact slow you down.
Alternatively, if you have cup added and you're near your top RPM range, ask to have minimal cup added (something like .060) which will drop your RPM somewhat, and also help with slip and cavitation reduction.

Good luck,

Steve

Thanks SteveDavid for the input, I am currently running at approx. 5100 rpms with the 25's and I hit my rev limiter with my 23 mirage plus's. The problem I am having is the 25s can be blown out easily out of the hole and the 23s do not. As far as I know the only difference is that the 23s are pluses and the 25 are not. I believe the plus is the cupping. I am considering moving to a 4 blade but I believe that I will lose a bit on top end. Any input would be appreciated. I am running a 33 Challenger with a ddc hull and ofcourse b1 drives. 6.2s for power. Thanks Dwight

It is not that easy what I have learned, If you change the cup it will also change the attitude of the boat and offcourse this will affect rpm and speed. If you cup near the tail of the blade it will increase bow lift and if you cup near the centre it will rise the back of the boat. This means that if you do it right you will have less drag and higher rpm and speed and offcourse the opposite if you do it wrong.

Torbjorn:rolleyes: