Hello;



Friend of mine have boat with next spec:
- weight 7.500 lb
- chine 9 ft
- lenght of boat 26 ft, ower all 32 ft
- engine disesel 4,2 TDi, with 320 bhp and 3.850 rpm wot
- Bravo 1 X diesel with 1,65 reduction, kavitation plate 1" lower than hull bottom, it mean 2.330 rpm on prop shaft.


With Mirage Plus 14,75x21" he reach only 24 mph at 3.900 rpm, it mean lot of slip.
He test other alu prop with 15,3x23 Solas and he reach 16 mph at 3.450 rpm and seccond later prop start to kavitate, no way to go plane. Engine just reach full rpm and prop cavitate like crazy.
Any idea what to instal on prop shaft?

Before he have smaller engine with only 240 bhp, 300 rpm more and boat it is plane nice with mentioned Mirage.


I am suggest him Signature ML500x20.


Any idea?


ps.
I know, that this boat is far away from this forum discusions, but anyway, perhaps will somebody suggest him good solution.




bye
Saso

We would suggest a 23" P-5 X five blade which is 15" diameter. This will reduce slip and load your diesel correctly. If pitch is a little high, we can down pitch prop to 21.5 to22".

Thanks,

Thom

I think the drive is too low if the Cav plate is under the keel.
I feel a full diameter Maximus is a great starting point for prop testing.

Brett