engine height

[fish46]

I have a suzuki df300 25" shaft on a 25 ft Parker cc 16 deg on a transom bracket with a 30" setback.
My question is how far above the bottom of the boat should the cavitation plate be with the motor in vertical position to the hull (normal trim at cruise speed)not at fuull speed and full trim.
I have no prop slippage in turns or in heavy seas.My cavitation plate is 2" above the bottom of the boat now.The motor is mounted on the second hole from the top.I am running a suzuki prop 3x16x18.5 top rpms are 5950 with a light load and 5750 loaded for fishing.If i raise the motor 2 holes that would be approx 1.5 inches higher and then the cavitation plate would be approx 3.5in above the bottom of the boat.

[eggsuckindog]

Your set back makes it a little tougher but sounds like you could go at least 1. It also depends on the prop and how much rake and cup it has and I'm not familar with Zuke props.

[Bly]

I have a 233 formula with 30 in flotation bracket, 250 yam 2 stroke. Im 4 higher on a 24 degree bottom . 51 mph at 5600. no cavitation or prop loss in any sea.

[Mr. Demeanor]

30" of setback is huge. Measure your height at the propshaft, not the cav plate. I have 15" of setback and my propshaft is 1/2" below the bottom at neutral trim. I run a Rev4 and it just starts to slip in heavy seas. Couldnt go any higher and actually going down one hole (3/4") probably wouldnt hurt performance.

[Mr. Demeanor]

PS. How are you measuring your setback? Measure from your drainplug in most cases to the front of the engine mounting plate.

[fish46]

I measured from the transom along the top of the bracket to the back edge of the bracket (stainless marine bracket)

[Mr. Demeanor]

Sounds good. I have seen some measure setback to the leading edge of the prop hub, back of hub, etc. etc.

[Honda Dude]

The general rule of thumb is that the leading edge of the cavitation plate with the engine fully trimmed down should be even with the bottom of the boat if the engine is mounted directly on the transom. The engine should be raised 1" for each 12" of setback if mounted on a bracket. So in your case the engine should be 2 1/2 inches above the bottom of the boat. That's the general rule of thumb. Now adding my personal experience: we have found that when hanging a fourstroke outboard, we can usually raise the engine 1 additional inch. This should get you very close, you can fine-tune it from there.