Posting this question for someone else.

150 Pro XS - the first couple of times to run wide open is about 10mph slower than we were thinking. It only has about 3-4 hours on it now. Should it get faster or is the jackplate way outta whack?

Depends on set up. But usually about 5% if you are looking for speed numbers.

I doubt you'll see more than 1-2 mph difference from break-in to normal operation unless you make some set-up changes.

10 mph off probably means you have some issues with your expectations. What boat is this on? What prop, etc.?

18XS with a 21 pitch prop

Try a 23 Tempest

Wrong prop

How fast should a Triton 18xs run with a mercury 150 with nothing in it but one person about 265lbs?

60ish

I agree with this number give or take 2mph.

Are your RPMS where they are supposed to be? I bet the prop needs more pitch as mentioned in the other post.

Oh and use a GPS, forget the speedometer, they aren't very accurate.

Generally speaking your boat will continue to get slower after break-in...what usually happens is you continue to put more stuff in the compartments...LOL...when your speed testing all factors need to be close, weight - includes amt. fuel, you, tackle, also air temp, water temp, wind direction, chop on the water...today's 150 class bass boats are not speed demons, mid to upper 50's with a full load is going to be normal...if you only plan on running one prop for all conditions you should be more concerned with is the motor running in the mfg RPM range in all air temps...bogging the motor down is just as bad as over revving...good luck with your new rig !

It was doing 51-52 with one person, no gear at all and 1/2 tank of gas

Too many variables--it won't be just the engine being broken-in that'll improve performance. Like said, boat set up, weather,water conditions etc,will be what determines how fast a 150 will push a hull.

I don't think you will see the 60 your thinking about, 55 is probably more realistic.

Get a jack plate and start prop 3" below pad!

Call Steve at Steve's Prop shop in Quitman!

I do agree with more pitch, you should speak with Steve at lake fork.