Hi corinmellor
My mate is running a MFA Spearfish which he started with a 100 Amp car ESC, 3S Lipo 5800mah 60C and a 3639-1100kv 800watt brushless motor.
Prop was a 50mm 2 prop 1.4 pitch.
The was quick, but, we changed up to a 4S Lipo 5800mah 40C.
The boat was quicker, but as it is a very stable boat.
We straight changed over to the 3648-1450kv 1600watt on the 3S with a 2 blade 45mm 1.4 pitch prop.
Getting into the fast end the boat was still stable and quicker.
So we changed last Saturday to the 4S Lipo and changed the prop to a 2 blade 40mm 1.4 pitch prop.
It's dam quick and still very stable.
GPS at 37KPH, if that's quick!!!!
The only change to the ESC was the cut out voltage for the different batteries and the start power from 10% down to 5% for better low speed.
The onboard Amp meter showed 72.88 Amps at full speed on a fully charged 4S battery.
I have a XK3674-1660kv 1600 watt sitting in my lengthened Swordsman which I have not finished so we may drop it in the Spearfish for fun.
Canabus