Hi, my younger son uses a 777 direct onto a 50mm prop shop prop through a kort nossel on his 27 inch tug, it has more!!!!than enough speed, runs cool from 12volt supply for about 1 and half hours. Will say that not all speed controlers like 7 pole motors and lower performance can be a bit iffy if not dangerous to the esc , do be carefull. Another of our club members runs a large 4o inch fishing vessel via 777 on 6 volts at a very good endurance rate and scale speed. I'm sure a word with Allistair will sort things out with you. Oh the other point is the 777 has a very short stub shaft with a brass spline affixed with a grub screw.not a problem just a solution to find!!!
Pirate