Progressive Seiltrommel Graupner 3771.40 The drum sports a progressively routed conical groove for winding up a rope. When maneuvering a boat close-hauled the boom is powerfully moved via clewline, using the smaller diameter drum. When running a boat before the wind, with
the boom at right angles to the hull, however, little tension is required at the clewline er). using the larger diameter drum
provides high winding speed under these circums-
tances, making for faster executed maneuvers.