Brushless will give you all the power you need with the right propeller and battery.
I have a 48" Sea Queen and use a 750Kv 36XX type with a 60amp controller and 11.1v LiPo and 35mm 3 blade PropShop prop. Use a Wattmeter to measure the current draw and adjust the prop to keep the motor and ESC within spec. Runs for about 20mins on this battery. Two props would make for a true scale model but my 34" Fireboat runs on the plane with one prop.
To get on the plane you need to keep the model light and with as little weight as possible near the bow.