Prior to launching this year, I had the boat maintained. The local Baja Dealer up sold me an "alignment" for $100.00. My boat is a 94 272 with a 502 mpi. Last season, the boat ran upper 60's, 67-68 mph. I had a bad year and was only able to use the boat a few times this year, however this year the best the boat will do is 63 mph. The boat still achieves 5000 rpm and I have 2 props, a 23" 3 blade and a 24" 4 blade. both props showed a decrease in speed??? Engine still sounds stong and has good compression all cylinders between around 145 with 2 at 135.

I can tell when I am driving the boat, when I start to trim out it seams like the boat is not coming out of the water, like not enough air under the bottom of the boat. Almost feels like the boat is "plowing" through the water when on plane rather than skimming accross??? Not enough bow lift since the alignment??? Is that possible??? Or could the drive have been put on wrong?? I have been told that it only goes on one way? Being that the prop is the same, the engine is achieving the same RPM this is the only explaination I can come up with, if so would love to correct and hope that no damage was incurred due to the mis alignment?

I doubt the alignment caused you to lose speed. The gimbal bearing would not survive very long if it were consuming enough horsepower to slow the boat.

It does sound like your drive is not trimming up high enough. Have you tried using the trailer button to bring it up higher until it blows out the prop and then bring it down a little? They may have moved the trim switch adjustment on the drive when they did the work and now its not trimming up high enough on the normal trim button.

Based on my experience this year with someone who REALLY knows about props, I would say that you have lost some of the cup in your prop. Losing some cup will allow you to still rev up to whatever but what you lose is "grip" on the water (speed loss) and that is also felt as loss of lift. The slip factor is what increases when this happens.

I live near Chicago and the guy is just south of Milwaukee so let me know if you want his number.

Dave

Is the rpm the same as before? If they both were 5000, then check the pitot tube (if you are using stock speedo). Run the numbers and compute your slip. Sound too high, check with gps...

I don't think alignment will cause loss of speed, but it will certainly cause loss of coupler.

yup, tried the trailer button, the prop does start to slip too much so I need to trim back down. It appears the trim button is correct.

How does one calculate the "slip"???

Could the drive have been put on wrong??? Or is it dummy proof??

What about some kind of rubber boot at the gimbal for the exhaust to go down and out the prop.
They say taking it off helps speed.

How do you determine speed? GPS, speedo, radar? That load did you have? What is your rev. limit? How hot was it (the air) compared to last year. Was the water flat or choppy? Were you going into or against the wind? Dirty bottom?

I can lose 4 to 10 mph depending on these conditions.

I also doubt that alignment could cause a problem other than mechanical. Here is the alignment procedure so you can see how alignment is attained, and what may occur if not correct...

thank you for all of the information. Now I am thinking about the prop!! I am going to attempt a new 24 this week and will post the results.