High Quality Content by WIKIPEDIA articles! The International 420 Class Dinghy is a double-handed monohull planing dinghy with centreboard, bermuda rig and centre sheeting. The name describes the overall length of the boat in centimetres (the boat is exactly 4.2 metres long). The hull is fibreglass with internal buoyancy tanks. The 420 is equipped with spinnaker and optional trapeze, making teamwork necessary to sail it well. It has a large sail-area-to-weight ratio, and is designed to plane easily. It can be rigged to be sail single-handed.