Engine height

[Itsme]

Advice wanted. Setting up the engine on my 13 foot Dick Sooy race boat. Bottom flares down to flat hull at stern. Turn fin 3 feet from the stern. Originally I placed a 2 x4 on bottom of hull protruding past transom and set the cavitation plate level with the hull (2 x 4). I will now be installing a jack plate 4+ setback. S & F member has a 4" plate, just waiting to hear back from him. Should I still set the cavitation plate even with bottom of hull with most of the adjustment to raise, or should it be set even higher than bottom initially? Thanks in advance.

[Will hedrick]

What engine you putting on it, lower unit? Prop? All will play a factor in getting the most out of it

[Itsme]

50 hp Evinrude to start. All stock.

[Will hedrick]

I would start 1" below pad and see what your water pressure is as omc like a little higher pressure then merc., then come up a 1/4 at a time until you start to lose pressure, as long as you are around 18 to 20 you will be good , put a nose cone on it if you want to surface it, I bet you will be about a 1/2 before you notice a pressure change

[Itsme]

Thanks

[OnPad]

Your cavitation plate should be above the bottom of the boat. With the remaining adjustment, up.

[Will hedrick]

On pad is the man,
With every boat comes customization, understanding your own boat through driving and tinkering, none of us can give you exactly what you need, but can lead you in a direction that we would go, more info the better, I love to see the 50-75hp motors running 7k myself,

[Will hedrick]

With my numbers comes the center of the prop shaft, I always determine 0 by the center of the prop shaft being exactly in line with the exact bottom of the boat(with all components being level on a level

[OnPad]

Will, I figured you were talking about P.T.P. or, X dimension.
I just wanted to make sure Itsme didn't mount to low, if he thought you was talking cavitation plate.

[Itsme]

OnPad, Thanks for the clarification. Yes, I took Will's post as cavitation plate 1" below hull pad.

[OnPad]

Itsme, cool little boat. Did you build it? Should be a blast with 50hp.
Usually, boats don't run very good dragging the cavitation plate around!!
Not a expert on your motor, but my guess is, a stock lower unit will start losing water pressure at approx, -2.5 to -3.5 inchs. Your best performance would be achieved higher than that, closer towards what Will said at even with the bottom of the boat. But you would have to invest in a race prop, and some sort of water pickup. Above #'s are prop shaft to pad, and just a rough guess.

[Itsme]

OnPad, Thanks. I did not build it, but slowly restoring it. It was manufactured by race boat driver Dick Sooy. He raced hydro's in the 50-70's.