If you have been a small (20 ft or less), powered boat owner you may have heard there is a CG requirement that the boat must be built with flotation. This build requirement does not apply to sailboats.
Part 183. Boats and Associated Equipment
183.1 – 183.810
Subpart E
Flotation and Safe Loading Requirements-Outboard Motor and Related Equipment Test Weights
§ 183.101 Applicability.
This subpart applies to monohull inboard boats, inboard/outdrive boats, and airboats less than 20 feet in length, except sailboats, canoes, kayaks, inflatable boats, submersibles, surface effect vessels, amphibious vessels, and raceboats.
Personal flotation is required for all persons aboard a sailboat.
Sailboats will sink. They stay afloat by keeping water outside the boat. If they turtle some boats will float because of captured air unable to escape from the hull.
Proper seamanship remands the skipper and crew to secure all hatches to prevent water ingress. Plan and provide methods to pump overboard all water.