I recently added a CMC jack plate to my 18 Sea Ark MV jon boat. I have a 60 hp 4 stroke yamaha. I now know I am not propped properly for using the jack plate. When I drop it dowen to "normal" position, all is ok, but when I jack it up I get almost instant blow out. I can tease it up to almost the max with trim and tilt, but blow out is pretty much a given. I actually gained 2.5 mph on top speed with a lot less trim tab. I know every prop mfg wants to look at rpm, but with the jack plate I know I am getting every RPM I have out of it. BTW, my top speed with only me on board with 14 gals of fuel is GPS 38.2. I really want to pick up even more top end speed, but want to also have some better bight with the jack plate raised. I do not really know of any body local to me that is willing to help me dial in my prop, so it loks like I have to try to get the closest I can with the info I have. BTW, I love this forum....very imformative.