What pitch/diameter is recomended

[Ifkyk]

I have a 1998 tracker pro 17 running a 1978 Mercury 85hp I bought this motor separately with no prop and I looked for answers on what to run but I’m still learning all this any recommendations or someone running something similar to this?
Thanks!

 

[Faztbullet]

First does it have trim? Also that motor s more like a 75Hp due to BIA rating.What is the primary usage for the boat? Fishing,water sports,cruising, how many people on board?

 

[Ifkyk]

I will pull a tube from time to time but for the most part it’s for fishing I typically have 3 people on the boat

 

[WesNewell]

Do you have the engine manual? It will list the gear ratio. What is it? Without that or info with a current prop pitch. It's just a guess. Maybe find a cheap 15-17P prop and go from there. You also need a tach (set properly).