The ornamental design for a boatfender, as shown and described.
FIG. 1 is a front perspective view of a boat fender.
FIG. 2 is a front view of the boat fender.
FIG. 3 is a back view of the boat fender.
FIG. 4 is a left side view of the boat fender.
FIG. 5 is a right side view of the boat fender.
FIG. 6 is a top view of the boat fender; and,
FIG. 7 is a bottom view of the boat fender.
The broken lines shown illustrate portions of the boat fender that form no part of the claimed design. The dash-dot-dash broken lines represent a boundary line and form no part of the claimed design.