Opinions/experience needed for prop selection on 90hp Johnson

[FBPirate95]

I have a 1985 90hp Johnson on a 1979 17' Marquis bow rider. I'm not sure the weight of the boat. Anyway, I got it all running last summer and put a new Rubex 14.8" dia x 17" pitch prop on her. My WOT rpm's are running 4200-4300. Way too low I know so I'm looking to go down in pitch. The question I have is what would be better for me, a 3 blade or a 4 blade? We aren't too concerned about speed since its mainly for just cruising the intercoastal and doing a little fishing here and there.

Anyone have experience with the 3 to 4 blade switch?

 

[steelespike]

Re: Opinions/experience needed for prop selection on 90hp Johnson

We need more info.Check "read this first" at the top of the main prop page.
Something isn't right hopefully its just the numbers.
It would take about a 6" pitch change top make up 1200 rpm.
An 11" prop would be like you might use on a house boat or big pontoon.

 

[FBPirate95]

Re: Opinions/experience needed for prop selection on 90hp Johnson

I know it looks odd, but the lower unit I have on my outboard is one I got from TashasDaddy early last year. It fit with a slight modification to the shift rod length, but when i researched it, it appears to have a different gear ratio then the old one. So I'm expecting to run lower RPM's than recommended. I'm looking to just get closer to the 5000 rpm mark. I'm looking at probably 13" pitch most likely.

 

[steelespike]

Re: Opinions/experience needed for prop selection on 90hp Johnson

Do you know the gear ratio? Do you have your speed at 4300?

You can find the ratio by pulling the plugs and carefully counting the flywheel turns to one prop turn.
13 would add 600 to 800 rpm.Might barely get you into it horsepower rated rpm 5.000.
If we had your present rpm and speed by gps it would help.