The ornamental design for a boattrailerself-centering support for boat keel, as shown and described.
FIG. 1 is a perspective view of a boat trailer self-centering support for
boat keel showing my new design, it being understood that the broken lines
are for illustrative purposes only and form no part of the claimed design;
FIG. 2 is a top plan view thereof;
FIG. 3 is an end elevational view thereof, the opposite end being a mirror
image of that shown;
FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 3.
FIG. 5 is a side elevational view as taken along the line 5--5 in FIG. 3.