Years ago, I read Orr Kelly's book Brave Men, Dark Waters about the SEALs, and one of the boats they used in Vietnam could go from (IIRC) 60kts to full stop in two boat lengths. Maybe your buddy read the same book...As a sideline comment. We have a 07 150 EFI Merc and found out that the prop is coupled to the output shaft via a sacrificial plastic coupler. You might check and see if it got cracked. Found out ours was damaged when a numb nuts buddy of mine was driving and thought he would slam it in reverse while going full tilt across the lake. Lucky the gearbox was not completely trash canned