That is large, If it were me I'd use a 900 size motor with a 2 to 1 reduction gear, and I'd use two 12 volt 7ah batteries wired in parallel to give extra run time and help with the ballast a hull that size would need, but then I'd only be looking for scale speed, if you want it to plane I'm sure some of the fast hull boat guys on here will be able to help you.