I ran 2 "12v" Graupner 700s NOT 8.4v or 9.6v (that would make a difference) in parrellal on 9 cells. 10.8 volts turning (2) 1-3/4" 2" pitch 3 blade brass dumas props. with a proboat esc 50 amp rating it looks like the one in your photo. I ran (8) 150' passes at FULL speed, I ran it hard, maby 13 mph in a dumas trojan I checked the esc and I could hold as long as I wanted. 5 minutes would have been possible, it beat the 5 second rule. but it was warm.