Average speed for 85hp motor on older boat

[Ozark Angler]

What is the average speed to be expected from an 85hp motor (regardless of brand, mine is Evinrude 2-stroke) from an older style hull like a tri-hull boat.

So far, I'm getting 39-40mph (GPS) with a 13x19-pitch 3-blade but I CANNOT get the motor to trim up more before the prop slips. I know there is more RPM range left so I'm thinking of trading down to a 15-pitch with a lot of cup or possibly a 17-pitch 4-blade with a lot of cup so I can trim the motor up more and not allow the prop to slip and get my RPM range higher.

My goal is 45mph or better at WOT. The boat is only 15.2 ft long and rides really smooth for a tri-hull.

So, what is reasonable and what should I expect?

[MassBass320v]

Sounds like an answer for the Setups page.

[Sacto John]

I have a 1977, 16 foot Streaker (I have a picture of my boat in the "Rare Brands" section on this site if you want to look at it) I have a 1974 85 HP Evinrude on the back and the fastest I have got so far is 41.2 on my GPS. I do not know if you are going to get much more than 40 out of your current boat.

[Ozark Angler]

Thanks for the reply. That's exactly what I was looking for. I figure 40 is all she's got but I just wanted to make sure.