[1][2][6] The design was built by MacGregor Yacht Corporation in the United States, from 1980 until 1985, but it is now out of production.
[1][2][7][8] The MacGregor 21 is a recreational keelboat, built predominantly of fiberglass, with wood trim.
It has a masthead sloop rig, a spooned raked stem, a slightly angled transom, a transom-hung rudder controlled by a tiller and a retractable swing keel.
[1][2] The boat has a draft of 5.50 ft (1.68 m) with the swing keel extended and 12 in (30 cm) with it retracted, allowing operation in shallow water or ground transportation on a trailer.
[1][2] The boat is normally fitted with a small 3 to 6 hp (2 to 4 kW) outboard motor for docking and maneuvering.