help setting up a 14' jonboat

[Jonboat]

ok iv got a 4'' jackplate a small 14ft lowe flat bottom boat. and a 1988 mercury 25xd. any suggestions on setting this boat up for best top speed? I also have a mercury quicksilver round ear chopper prop its a 18p but looks pretty big didn't know if I could use this or if it would be worth even trying it.. any help would be great.

[champ20B]

ok iv got a 4'' jackplate a small 14ft lowe flat bottom boat. and a 1988 mercury 25xd. any suggestions on setting this boat up for best top speed? I also have a mercury quicksilver round ear chopper prop its a 18p but looks pretty big didn't know if I could use this or if it would be worth even trying it.. any help would be great.

I ran a 1997 25 twin cyl Johnson on a 14ft Lowe that had a flat bottom. This was a bench seat type with tiller steer. I could run a 15 pitch with good performance and economy with one or two persons aboard at 31-34 mph. The Mercury you have might be different though. My OMC was a torque monster at 31+ cubic inches. I think a 25 merc was a 22-24 cubic inch that needs a bit more rpm to make power with a similar gear ratio. If this was my project, I would start at a 13" pitch and check the RPMs then compare that data to factory rated RPMs. Every extra inch of pitch can be worth +- 200 RPM lower or higher.