My rigger has never been on the water running yet, but as soon as water is water and not ice it will
My rigger has a os cv-r.12 engine, I dont think boats this small need a water cooling (its just more stuff ya need to add to the little boats). First off my rigger is smaller than almost any .12 rigger ive seen its, front sponsons are 8" long and 1 5/8" at the widest point on the top the total length of my tub is 16 1/2" so comparing your boat to mine isnt really to good (yours will prob float) lol
Paul