The ornamental design for a propellerguard, as shown and described.
FIG. 1 is an aft elevation view of the universal propeller guard, showing my new design;
FIG. 2 is a fore elevation view thereof;
FIG. 3 is a reduced left side elevation view thereof;
FIG. 4 is a slightly reduced right side elevation view thereof;
FIG. 5 is a greatly reduced top plan view thereof;
FIG. 6 is a greatly reduced bottom plan view thereof; and,
FIG. 7 is a reduced aft perspective view thereof.
The broken line showing of portions of the propeller guard is included for the purpose of illustrating environmental structure and forms no part of the claimed design.