88 150 mercury xr4

I have a 88 venture with a 88 mercury 150 black max xr4 with a 24p laser 2 prop it runs about 49 but won't lift the bow of the boat when I trim it and everything I've read on theses boats say they will run low 60s. I'm just wondering if the prop size is my problem or is there something else wrong with it

My truck gets 22 mpg unless I'm towing my cruiser, then I get about 16 mpg.

That's the kind of comparison you are trying to make when you say "some boat" will make the low 60's.

Is that with only the driver on board, no gear, 1/10th a tank of gas etc etc.

What does your tach tell you? are you getting into the wide open throttle range for the motor when at full throttle? If so, you are propped correctly and no change in pitch or diameter will squeeze out any more speed.

What model is your boat? is it a fiberglass hull? have you weighed it to compare what it "should" weigh compared to what it does. If the hull is "water logged" you are potentially carrying a lot of extra weight = less speed and poor "profile" relative to the water line.

Many questions you need to answer before you start looking at the prop to improve performance. Unfortunately the answer is not as simple as go with "prop A" and your issues will be cured.

It's a 88 venture tournament edition fiberglass boat it's turning 4900 Rpms at wot according to my gauge and that's with nothin in the boat but 3 battery's and a half a tank of gas. And the other boats I was looking at is the exact same boat and motor

The boat never sits back on the pad when running wot and trimmed up the nose of the boat stays the same as it would just cruising

Sounds like you have "too much pitch" amongst any other potential issues.

I believe the WOT range on that motor is 5000-5600 rpms. If you are only getting 4900 with a practically empty boat your motor is working way too hard to try and turn the prop. What's it doing with a few passengers/junk on board.

Minimally I would suggest you should be running nothing more than a 21 pitch (same diameter) given your numbers.

It's a MYTH that MORE PITCH = MORE SPEED, unless you are running way too little pitch in the first place which is preventing you from running full throttle without over-revving.

You are not making your WOT range so the motor is "loading up" trying to turn a prop that is too big.

High heat/humidity that you get in the summer compounds the problem since the motor can't breathe as well - this often shaves another 10% off the performance, which in some cases could require running even less pitch than you would in the spring/fall.

Anytime you can not get your rpms above 5000, and on this model I would shoot for 5250, it is not producing max horsepower and it could possibly damage your engine.

This still wouldn't address your bow profile which must be caused by something else - weight balance would be one possible cause, soggy hull would be another.

Again I go back to weighing your boat. If you have two identical boats with identical motors, rigged the same carrying the same amount of weight but one is significantly outperforming the other then you have an undetected weight issue or some anomaly in hull (which could be a hook in the hull - crustaceans or other cooties on the hull etc).

If you have the original "small" gearcase which it sounds like (laserII prop), it a 1:78 ratio and a 24 is a tad big. Also if raised to high the prop will not lift the boat due to its diameter, If its on a jack plate lower it 1/2 inch. That hull if the 17ft with a 150 will run in low 60's as rigged many of them...