Raised my motor, but questions...

[Capt Terry]

I never had to consider where the A/C plate was during the first 37 years of running Mercs on my '76 20' Seafari. Why? probably because both engines were sold & installed by Frank Brown, one of Moesly's race mechanics. Three years ago I bought an ETEC, then I started hearing about about height over the keel from the ETEC owners site. My ETEC dealer raised my ETEC twice and I raised it again. Last week Skippertee was riding in the stern jump seat as I cruised at 30-32 mph. He said the A/V plate was positioned just right and said Moesly recommended 1.5" above the keel, which is what I measured after the last height adjustment. BTW, I have no engine bracket like Bushwacker. As others have mentioned the propeller characteristics play into this too. I have tried a few props, but got my best results for WOT rpm and best wakeboarding speed control from a 5 blade High Five. The other props worked pretty well too, but didn't quite get it to the recommended WOT rpm.

[McGillicuddy]

Capt Terry speaks truth.
1-1/4 " is fine. going up 1 more notch will probably be fine. 4-5 blade will help.

Other issues to consider:
1. What is your prop? Make/model (defines shape and what it was designed to do), diameter, and pitch.

2. What is your max RPM at WOT with a full load?

3. Another potential detriment is yer motor - if i'm not mistaken (and please correct me if i'm wrong) , its what Mercury sold as a 2+2 fishing motor. It was designed to save fuel at manatee zone speeds by firing 2 cyls, and then take off as the other 2 cyls fire as you reach high 2k rpm. means your low planing speed is compromised because that 2300-3200 rpm range is virtually non-existent. Thus your putting along or cruising over 20mph.

As Capt Terry noted 4 blade or 5 blade may help.

Post some answers and give the performance guys, something to work with.

Good luck. The 18 is a favorite among its owners and you should be happy!