I think I have finally got the prop I need.
The redbay 6.1 is quite heavy and (and mine is a 2002) a deep V, mine has six seats and I tested with about 90litres of fuel and three adults on board.(admittedly young adults, but lighter than me!)
STD prop that came with the boat
3 x 14 x 21 WOT 5600rpm Max Speed 34 knots
Had it repitched by Castle Marine
3 x 14 x 19 WOT 6000rpm Max Speed 35 knots
tried a Suzuki S/S Solas
3 x 14 x 20 WOT 6050rpm Max Speed 35.4 knots
tried a powertech S/S
3 x 13.5 x 21 WOT 5900rpm Max Speed 32.1 knots
bought a S/S Michigan Ballistic WOW !!
3 X 1/8 X 21 WOT 6000rpm Max Speed 38.3 knots
Much more grip, fine balance, reduced cavitation. lots of cup and looks like bits missing off the blades buts works, great overall
Tried the S/S Michigan Ballistic
3 x 13 3/8 x 19 WOT 6200> if you wanted and 35 knots (no good but could be if you had a heavy boat with dive gear, shot onto the plain.
I would like to thank Carwyn (realised spelt his name wrong) at Castle Marine for all his patience, advice and sourcing this prop.
I feel I now have the best speed, best grip and should be the best boat speed for engine speed hence improved MPL
Ps I have heard that you have to be careful with these props as they can give too much stern lift and cause other issues such as engine overheating, mine hasn't as it is heavy.
Will have to wait for the next Ty Calch cruise with the BS brigade for more information.
For any of you looking for that special extra, well worth a try.