We are getting there...
Tested reworked High Five 19P. 6mm holes drilled behind each blade, added more cup to each blade but left pitch the same at 19P.
Before modifying prop boat would struggle to gain revs. 0-30mph was about 10 seconds, this is about the same acceleration as the current FW180 with the 135hp 4pot, as tested in the boat mags. This reinforces my believe that my boat would not pull the skin of a custard in any hurry...
Took about 10 seconds to pull me out slalom - not to 35mph but just to get me on top of the water. My previous 180 Sea-Ray with 130hp 4 cyl and 500 hours was about the same looking at and timing the old videos.
17P 3 blade aluminium prop was better at about 8-9 seconds 0-30mph, slalom up was about 9 seconds, but WOT was 34mph limited by the rev limiter.
Yesterday the modified prop showed promise. 0-30 is now just over 6 seconds, and pulling me up slalom now 6 seconds. The holes allowed the prop to vent and the motor to rev up to 3500 - 4000 rpm on pull off. This puts the revs in the high torque zone and performance is now acceptable, not great or what I expected but acceptable enough to not have to sell the boat.
WOT now about 44mph, up from 40mph, so the increased cup has helped here too. Still really easy to hit the rev limiter.
Fuel consumption is currently very good, been out 3 times on the same tank..

Motor runs sweet, no miss, no stalls, idles smooth and quiet, just lazy to rev up?
Next step is to take boat into marine mechanic this week for a full check and see if he can find anything that might help, followed by an ECU remap and rev limiter increase. Found a local crowd that can remap the ECU module and raise the rev limit and perhaps adjust the fuel curve for more torque
Hydrofoil has been removed so handling is improved, and somehow the current modified prop seems to really help the boat stay stuck in the water. I can now confidently chuck the boat around at reasonable speeds and it seems safe. I feel confident I can now flick the kids around on the inflatable with out sinking the boat.
It has been suggested that I should have bought the 300hp V8... wish I could afford it.. but I am not expecting 300hp performance, just better than my old 130hp Sea Ray and at least close to similar boats with similar motor packages (ie my mates Sea Ray 205 with the same motor which seriously outruns me.. by a long way..).
Will post up anything my mechanic finds this week.