Welcome to boats.
When accelerating to get up on plane, the engine should be all the way down, then raised after the boat is on plane.
Well sir, that depends on the boat and what's in it. I had an 18' alum. bass boat with a 90 Merc. and SS Ballistic 24P prop., 1 hole up off the transom. The picture in my Avatar is that boat kissing 50 with just me. My fastest hole shot was with the engine at 90* to the hull. Hole shot was firewalling the throttle, the prop would blow out, the RPMs would shoot up, the prop would grab and blow out for about 3 oscillating cycles (blow/grab, blow/grab blow/grab and hold....... and it was gone.
I had a Caravelle 18' tri-hull with a '72 125 Johnson, 17 or 19" pitch newly available SST prop (forget which) no PTT (till '73 engines) and the tilt pin was set in one hole and left there rather running just under 40 alone, or in one case at a company picnic, somehow getting 5 skiiers up simultaneously for about 200 yards before one fell off. Most were light weight folks on 2 skis. I didn't have instruments on that boat other than the speedometer so I don't know where my RPMs were when running.
Had a1988 18' Ranger BB with a 115 Merc "Tower of Power", 19P original SS Laser which was ported. The engine was usually vertical for the shot. The ports would let the prop spin up fast in the hole shot getting on plane fast and once up and moving right along, the holes would close and it was like overdrive in an old stick shift car....you felt the jolt. I slalom skied behind that boat with my son driving, same engine position.
