Acting on advice from Canabus I fitted a Turnigy 3648 1450kv motor and Leopard Hobby (Hobby Wing) 120a ESC to my Dumas Chris Craft 1930 runabout. Prior to the conversion it was fitted with an MFA Torpedo 850, the difference is remarkable, the boat lifts on to the plane effortlessly and after a typical mixed 45min run on two 3s 5000 mah Lipos the motor temp is under 50c and the ESC and batteries are not much over ambient temp. this weekend I spent more time than usual at higher throttle settings and the battery voltage after nearly an hour just dipped under 12v for the first time.
Still experimenting with props to try to find the optimum setup, tried 35, 40 and 42mm props,(all X types) with the 35 giving the best performance so far.
Testing with tachometer the motor unloaded gave 18600rpm, 42mm gave 12000rpm, 40mm 14000rpm and 35mm 15000rpm
Currently running the original Dumas 3 blade bronze prop which looks great (polished) on display but seems to spin rather too easily (17500rpm) and moves less water in the test tank (paddling pool)
When it comes to "scale speed" I have attached a pic of a full size version of my boat that is fitted with a hot V8, so fast brushless models are not that outlandish when full size 80 year old Chris Crafts can hustle along like this old lady
Hope this is of some help