Doing some real world testing on my 34 LRC Californian with the 210hp cats,
1. first props 3 blade - 23 x 21(with cupping) - WOT = 18.5 Knts with full load of fuel(250 gal) and water, 12.5 knt cruise around 2200 rpm.
2. new 3 blade prop 21 x 23 WOT = 17 Knts at 2750 RPM with full fuel and water, cruise is now 12 knts at 2400 rpm
3. Now looking to buy a set of 4 blade props to try again
1. first props 3 blade - 23 x 21(with cupping) - WOT = 18.5 Knts with full load of fuel(250 gal) and water, 12.5 knt cruise around 2200 rpm.
2. new 3 blade prop 21 x 23 WOT = 17 Knts at 2750 RPM with full fuel and water, cruise is now 12 knts at 2400 rpm
3. Now looking to buy a set of 4 blade props to try again