Ken, my rig is a totally different animal, a 20 with a single Hermco bracket and 25" motor, but I ended up having to install a 3" setback jack plate and raise it all the way up! My AV plate is now about 6 1/8" above keel, with a total setback of 33", so my (AV plate height)/setback to get the AV plate above solid water works out to be 2.23" per foot of setback!
I think that number is primarily dependent on the shape of the water flow coming off the transom. Water flow trajectory is probably affected by boat weight, deadrise angle and speed all of which is different on your rig, but I suspect that if you used a trade factor of about 2" per foot of setback, you would be would be in the ball park. I cruise at 27-28 mph, with a WOT speed of about 42 with a heavy load and min planing speed of about 12 mph with a good 4B stern lifting prop and handling is good with no blowout on sudden hard turns. Only problem is I can't trim motor higher than about about 50% of max or it'll start to porpoise, but I think that's basically a CG/weight distribution issue, as more gear in the cabin eliminates that problem.
Don't know what the hole spacing and total range is on the Zuke, but my E-TEC has 4 holes spaced 0.75" apart, so total height adjustment range on my motor is 2.25". If you used the 2.0 inch/ft trade factor and mounted motor so you could move it down 1 hole and up a couple holes, I suspect you'd probably be able to get to optimum height.
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