Prop Selection, 125HP 20' Seafari

[Max_Florida]

Well, after messing around with multiple older engines that were just problem after problem, I finally decided to just spend the money on a new motor.

I ended up going with a Mercury 115 Pro XS(rated ~125 at the prop)

The dealership that put it on gave me a 13-1/8 x 16 stainless prop, and told me I could switch it out with them until I found one that worked for me.

With 3 big guys, a full tank of gas, big cooler full of ice and fishing gear these were the performance numbers:

WOT: 5700 RPM, 37MPH
Cruise: 4000 RPM, 26 MPH

In sloppy/choppy 2ft seas it fell off plane at 3500 RPMs, or around 17mph.

The max RPM on this motor is supposed to be between 5000-5700.

I really only use this boat for spearfishing in the Gulf, typical run is ~20-25 miles and the usual conditions are 1-2ft slop. My primary concern is cruise speed/efficiency and being able to stay on plane at lower speeds when it's sloppy. I'm thinking I should try something around 14x17. Keep in mind this is the "Pro XS" model of the 115 so it's supposed to be closer to 125 at the prop.

What do you guys think?

To add:
I have the Smartcraft gauge so the tach is 100% accurate(I hope)
I will double check that the AV plate is 1.5" above the keel