Motor Boat RC - spiral vase printable

I wanted to make a bigger boat so I just scaled up my boat http://www.thingiverse.com/thing:204303 to 200% and edit the bow.
It can be printed in two parts each 162 mm high.
Additional it has now a propeller drive and rudder control.
It is designed to use my Roxxy BL-Outrunner which I already used for my plane http://www.thingiverse.com/thing:86982
But this Motor is so powerfull that it would drive the boat to fast without controlling the speed. Currently I am waiting for a receiver