Motor Height???

[defiant0ne]

Originally Posted by DW

Suggest you go to the third hole first. Until you try the third hole you won't know if you have it right. If the third hole is too high, then back down to the second hole. This will best assure you have the right solution.

Find a partner to drive your boat so you can easily see and photograph the position of the anti ventilation plate relative to water at WOT.

This is the most important adjustment you will ever make to your rig!

I tried out the 99 Merc 125 in the third hole. Results below:

The first run:
Full tank of gas
2 adults
17 pitch Spitfire X7 prop
Max speed: 36.1 MPH @ 5250 RPM
Water condition: Good-no wind

The 2nd run:
3/4 tank of gas
1 adult/1child
19 pitch Spitfire X7 prop
Max Speed: 38.5 MPH @ 5000 RPM
Water condition: Choppy- 15-20 mph wind

The motor performed well but not the gains I was expecting. But it did seem to not have to work as hard when I put the throttle to her. And since the motor was already raised, I did not have to trim it up as much to get on plane.

The only negative I witnessed was when the motor was trimmed all the way down it ran rough (vibrated roughly). When I trimmed it up slightly it went away. I never had that issue when I had the motor mounted flat to the top of the transom.

I still need to video/take photos of the anti-ventilation plate while on plane to see where the motor is at.

d1


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Another data run:
1/2 tank of gas
1 adult
19 pitch Spitfire X7 prop
Max Speed: 39.9 MPH @ 5200 RPM
Water condition: Calm, 10 mph wind

[yarcraft91]

When I got my current Alumacraft, the motor was mounted in the top hole. The lower unit threw a lot of spray on plane. Raising the motor one hole reduced the water spray dramatically and gained about 5 mph. Raising it another hole minimized the spray but only gained 2 mph. I left it mounted in the 3rd hole. The big gain came from not wasting motor power throwing huge amounts of water out to the sides due to the anti-cav plate buried in the water.

Good news it looks like you have the ideal props for your outboard.