Another motor height thread..

[Azoutdoorsman]

Hello I'm new here. I've been studying build over the last couple years but after buying a triton bass boat I've put my Lowe 1467wt on the back burner for a few years now. Due to the original 5hp short shaft mercury prop being barely in the water, I figured I needed a long shaft motor when I bought my new mercury 9.9 4 stroke in 2014. With this set up I've noticed that my anti cavitation plate is about 4 inches below the hull. When loaded with 2 guys and gear around 400lbs I've noticed if I trim the motor to the 3rd trim position and the front seat passenger sits in the bottom of the hull at the bow it basically doubles the top end speed and has much better controll. How much will an adjustable jackplate help my case if any?

 

[KMixson]

With the anti-cavitation plate being so low you are creating drag by the motor having to push the area above the anti-cavitation plate through the water which robs you of speed. If you raise the motor you may find more speed.

Now on the other side, if the anti-cavitation plate is above the bottom of the boat the prop may not get a good bite in the water and rob you of speed also.

 

[Zum]

Pictures can be deceiving but in the last photo it seems your anticavitation plate is 3/4 inches below your hull.? Not knowing the boat, have you ever measures the stern height?

I'd try raising the motor, especially if it's only clamped on...probably put some type of shims under the bracket and raise it as high as the clamps are safely mounted.

Sent from my SM-T350 using Tapatalk

 

[Azoutdoorsman]

Pictures can be deceiving but in the last photo it seems your anticavitation plate is 3/4 inches below your hull.? Not knowing the boat, have you ever measures the stern height?

I'd try raising the motor, especially if it's only clamped on...probably put some type of shims under the bracket and raise it as high as the clamps are safely mounted.

Sent from my SM-T350 using Tapatalk

So I just measured the transom this morning. It is right at 18.5 inches. Even though it is a clamp on, I only have about 1 Inch to safely raise it. I think I'll have to throw a jackplate on it here pretty soon to get it up the 4 inches or so it needs. Thanks for the picture for motor lengths.

 

[turbotodd]

If you have to go to a jack plate, depending on it's thickness, you should be able to move the motor up even more. A 5.5" jack plate can usually allow you to move the motor up another 2 inches or so beyond what you'd normally be able to if you were just hanging the motor on the transom. I have in the past had to drill 4 new holes in the jack plate to get it up high enough to run properly but I'm dealing with duck boats mostly-which are a little different-they're move of a "speed" hull than a pleasure hull; or at least that's the way I look at 'em--since the owners tend to favor speed over anything else, for whatever reason.

 

[Azoutdoorsman]

Thanks for the info. Heading to the lake for the weekend right now. Gonna do some actual testing then find a jackplate in the next couple weeks.