The ornamental design for a waterrower, as shown and described.
FIG. 1 is a right perspective view of a water rower showing the new design.
FIG. 2 is a rear view thereof.
FIG. 3 is a front view thereof.
FIG. 4 is a left side view thereof; and,
FIG. 5 is a right side view thereof.
Any shading and cross-hatching are not features of the design but are utilized to illustrate the surface contours of the crawfish pie design in the drawings. It will be understood that the dashed lines presented in the drawings are for illustration only, and do not form a part of the claimed design.