The Bay Hen 21 is a cat-rigged sharpie with gaff-headed sails built from 1984 to 2003 by several US builders including Custom Fiberglass and Sovereign America.

The design is based on the Lightfoot Sharpie designed by Bob Johnson, creator of the Island Packet Yachts series of boats. The Florida Bay Boat Company, owned by Trane bought the molds and Trane designed a new deck and cabin for the hull to create the Bay Hen 21.

It has twin, retractable centerboards, mounted side by side in separate trunks. It displaces and carries no ballast. The boat has a draft of with a centerboard extended and with both retracted.Henkel, Steve: The Sailor's Book of Small Cruising Sailboats, page 85. International Marine/McGraw-Hill, 2010. A small outboard motor can be mounted in a stern well, forward of the rudder. It has a hull speed of .

It has two berths. The galley is located under the companionway ladder and is a pull-out design. Cabin headroom is .

References