2007 Evinrude 115 ETec Low RPM's at WOT

[mralda]

Hello, I bought a 2008 Zodiac 650 Pro Open (21'4") with a 2007 Evinrude ETec 115hp. The engine came with a 14.5 x 21 3-blade aluminum propeller (#763469) and could barely reach 4500 at WOT. I recently replaced the prop with a 4-blade composite propeller (ProPulse) 14 x 15". The boat is reaching about 5200 RPM at WOT, but I have lost a lot of speed in the process... 19mph at 3500rpm vs. 25mph at 3000rpm. Do I need to go to 14 x 14" to get that extra rpm's at WOT? What engine damage occurs when you do not run recommended rpm's at wot? Typical load on the boat is 2 adults, 2 children and 30 gallons of fuel (say 700 pounds), my guess is the boat and engine weigh around 1750 pounds. We almost never run the boat at wot and prefer to cruise at 3000 rpm (less engine noise). By the way, acceleration is amazing!... but I miss my cruise speed badly. Thanks for your input.