Technical - Surface Drive Question

[Footloose]

I am trying to dial in a project boat which has twin 425 HP 502s and a pair of arneson drives. Questions to perormance prop folks are getting me very inconsistent answers. With I/O, Inboards, and even outboards, you know a prop is right when you can pull the engines WOT RPMs with them. If you can't, the props are probably too large (over-proped)

Is this also the case with Arneson surface piecing drives/props since when up on plane these props are supposed to be half in the water and half out?

[MOP]

The props do run 1/2 out of the water, below is an excellent article on surfacing propellers.

http://www.simplicity-marine.com/surfprop.htm

[Boatless]

The propellers are, when trimmed correctly, only 50% submerged.

But, the same theory applies to being able to pull the propeller.

With normal slip, 10%, you should be at max rpm the speed within 10% of the theoritical speed.

If your speed for example is within this 10% range but you are down on RPM's, then you either need to reduce diameter or pitch or a combination of both.