Nick................it sounds like your motor would strain quite a bit and run hot.............a 4200kv only 48mm long in a 40+" boat........did i read that right? Man if it works thats great, but i would think more like a 36x74 feigao 12XL-14XL on the 6s would be a cooler running setup at the minimum and certainly Ryans suggestion of the 580L would be optimal......just my 2 cents.....i've been known to be wrong before though.

Nice lookin' boat Wet...........