Mounting position for outboard engine

[Harleyfxdl]

I was reading the performance bulletins for Yamaha outboards. They tested a single 225 4-stroke on the back of a 258 Voyager.
http://www.yamaha-motor.com/assets/prod ... -GRW-B.pdf

I figured this would be close to the 200 I have on the back of my 208 Adventure. I noticed in the test they had the engine set on mounting height #3. I counted 4 mounting holes on my engine. Do you count from the top or the bottom? My engine is set on the second hole from the top, does this mean that my engine is too low, hence the low top end RPM?

 

[BobP]

Per Yamaha owners manual -

"Mount the engine so that the anti-cavitation plate is in alignment with the bottom of the boat."

The anticavitation plate is the horizontal plate that extends all the way to the back of the lower unit, it has the steering trim / anode mounted underneath it.

 

[catch22]

I think you can get away with the anti-cavitation plate around 1 1/2" above the keel. Especially with the Euro transom.

 

[Curmudgeon]

I've played with the mounting height of three different boat/motor combos. And "even with the hull" was too low on all three. Conventional wisdom says start with the cav plate at least even with the hull, then take it for a run. Optimum performance will most likely occur when the plate rides just a tick above the level of the water when at speed. Could be the third hole down, might be the second. You'll know when it's too high by the blowout on rapid acceleration or tight turns. Sure, it'll work in lower holes, but you won't know what "optimum" is until you search for it ... :?