I am struggling a bit here ...
Most of my propeller tests are unreliable, on account of the hull fouling problem over the last couple of months.
I am told that my boat - an 8.5 metre Scorpion with an Etec 250 (and heavy arch + radar and an 80 gallon fuel tank) attained 44kts at 5800 RPM when "tested" before I took delivery. Even pre-fouling, owing to a problem with the initial propeller being faulty (slipping against its rubber hub) I have never been able to reproduce this.
The prop is a 25" pitch Renegade (4-blades). Before the growth set in (about a week!) this prop gripped the water well and had strong acceleration.
Talking to Scorpion, it seems that 19" pitch props have been fitted to some Scorpions and that these might give better performance. Everyone says that selecting props is a "black art" but it would be really helpful to know the following about your boats (ideally 8.1 metre and 8.5 metre)
Size of boat and fuel tank
Propeller fitted (make, name, pitch, number of blades)
Top speed attained (in kts)
Max RPM at which top speed was attained
Your view of how well it grips the water
I am looking for top speed (ideally 45kts plus), economical cruising (at around 35 kts) and good grip. Is this attainable on my boat?
I really don't understand how reducing the pitch so dramatically can improve top speed.
I look forward to hearing about your experiences.
Thanks for your help.