propeller help

Was hoping some could help me out.. Had my boat out this entire weekend and it was great I have a 16 foot center console with a 85hp Force thats now running tip top

My question is when i go to get on plane with my boat it seems like the engine is working pretty hard to get it on plane... 1 person in boat im 220lbs once its on plane the top speed is about 32 35 mph ... The boat doesnt have a tachometer but once it planes off im back the trottle back to about 3/4 and just cruise... Pulled the boat out today and checked the prop


I got some numbers off of it and was hoping if anyone could tell me if its right or if i could change it to maybe help the holeshot and still have a moderate top speed when cruising... Thanks big time

PROP NUMBERS
H3477 on 1 blade
17 on another blade


this is a 3 blade prop is there a difference going to a 4 blade prop

Re: propeller help

Probably a 17 pitch. You may be able to drop down to a 15, but you really need to get a tach to check so you don't overrev the engine. ( going from a 17 to a 15 will increase the RPM about 300-400 )

Re: propeller help

thanks

im tring to find a 15 diamer prop with a 17 pitch i think the bigger diameter will give me the volume efficency i need to get on plane and the pitch will still allow me to keep the engine at a safe rpm level....

Re: propeller help

You're engine won't take a 15" diameter prop. Just select a pitch. The prop manufacturers do the design work to best match the dia and pitch.

Re: propeller help

You really can't tell much about the setup or the motor without rpm and speed.
I've seen motors that had sluggish hole shot yet were at max rpm at wot.
Without a tach if you drop 2" you put the motor 400 rpm over its limit
and no way to tell.If it displayed other problems you might raise the pitch making it lug also bad for the motor. A tinytach is about $47 and easy to install.
Generally diameter isn't considered in prop selection except to be sure it will fit.
As pitch goes up diameter generally goes down and vice versa.
A 4 blade 16" pitch should improve your hole shot and keep your present rpm(?)
about the same.