Vast difference in performance when used strickly on water, have a OS .46FX in mine and felt it was pretty slow when using it from land and with wheels, wheels removed and less drag I'm happy with its flying. Think the OS .52 would be OK when strickly used from the water.
I'm guessing you fly from Grass
I'm going to agree with MinnFlyer,, a 52 is going to be marginal,, All things considered, weight, small wing area, higher wing-loading,, you'll want more power than a flat bottom airfoil type plane like a Cub normally would need... I'd go with a 65-70 range engine myself