Prop pitch amp boat trim

Like a million other guys I&#3

Like a million other guys I'm trying to figure out the perfect prop without testing.
So I have the basics on RPM and WOT with the engine trimmed down I get ~42mph. When I trim the engine up and get the boat out of the water I pick up more speed and and of course RPM. Trimming up and down a hair at a time I get top speed of ~47mph. At that speed I still have about 400 rpm to manufacturer red line. Which I believe is 4800rpm for a 1989 5.0 Cobra?
Do I have an additional 2 / 4 inches of pitch for more top end?

Actually the specs for a 1989

Actually the specs for a 1989 5.0 is WOT at 4000-4400 so if your already at 4400 then that's it especially for a 20 yr old engine. Not sure what boat you have it in but I would say that 47 mph is pretty darn respectable!

"Yeah, it sounds like you'

"Yeah, it sounds like you're about there. I have an 84 5.0 stringer on a 19' cuddy cabin, can trim out at just about 44 mph (right at 4400rpm) with a 19 pitch stainless steel prop. The engine whines a bit, but she'll do it. Cruises great at about 3200 - 3300 rpm and about 32 - 35 mph."

"Thanks, Especially for the re

"Thanks, Especially for the redline. And you are right, 3200-3300 rpm / 33-35 mph all day long and not even break a sweat.
FYI it is a 1989 Bayliner Capri I bought new August of '88 and have enjoyed for 20 years. Pulled alot of tubes, skier's, drank alot of beer.
Running 19" Stainless Viper II for the past 6 years. I'll never go back to Alum. Outside of tune up's, & water pump's, I put on a new lower unit 6 years ago, yeah milky oil & freezing temps...not so good. Replaced the main drive shaft & shift cables 4 years ago, cost a grand. All in all 20 years, every summer a great boat.
Jim
p.s. Now I'm religious about changing all fluids, oil, lower unit, powersteering, lube everything..."