Boston Whaler Prop

[Brando_]

Hello,
I just finished a 3 month restoration project on a 1985 Boston Whaler. The motor is a 2006 4 stoke Mercury EFI 25 HP with an 11 pitch 3 blade prop. Wide open throttle I am getting about 23 mph and 4700-4800 RPM. The max RPM is 6000. The hole shot is decent with one passenger in the back. With about 320 pounds in the back with all passengers it is about 5-8 seconds to plane. I have a lot of room with the RPM not sure about the speed. I want more speed but don’t want to compromise the hole shot too much more. Maybe just stay with this prop and get a new one? What about 4 blades?

 

[jimmbo]

Welcome to iboats

Sounds like you can drop down a bit in Pitch, which will raise the RPM and improve the Hole Shot. If the tach is accurate, you are quite a ways from the 6K limit. Even though with less Pitch, which you are likely thinking, lower top speed, the engine will be running nearer it rated RPM, and is making more power, and you could end up going faster.
I am assuming that the Engine is in good condition and is in tune.

Adding a Blade will kill your Speed and drop the RPM.
The best way to get more speed, is simply more Horsepower.

 

[QBhoy]

If it’s a 25hp. I think you’re doing well and maybe check the tachometer is defo good. If it’s a 250. Not so much.