The Hornet dinghy is a 16 foot high performance dinghy designed by Jack Holt

Jack Holt (dinghy designer)

Jack Holt, OBE was a prolific designer of sailing dinghies. His pioneering designs of dingies using plywood did much to popularise the sport of sailing in the period immediately following World War II....

 in 1952.

It is sailed by two people, with either a sliding seat ('plank') or a single trapeze

Trapeze (sailing)

In sailing, the trapeze refers to a wire that comes from a point high on the mast, usually where the shrouds are fixed, to a hook on the crew member's harness at approximately waist level...

, or where neither plank nor trapeze is fitted, by three people. The Hornet is a restricted class meaning that its external hull measurements, sailing weight, sail measurements, and mast dimensions and weights are controlled, but the hull's interior layout, centreboard

Centreboard

A centreboard or centerboard is a retractable keel which pivots out of a slot in the hull of a sailboat, known as a centreboard trunk or centerboard case...

 and rudder have few restrictions.