In the water, buoyancy must be immediate. A life jacket is a personal flotation device designed to keep a wearer’s head above water and to provide a stable floating position, even if the wearer is unconscious.

Modern life jackets use foam or inflatable buoyancy chambers and are colored for visibility. SOLAS and national rules specify performance standards, including turning ability and freeboard for the mouth. Different types suit different duties—work vests for deck operations, full lifejackets for abandonment.

Crews and passengers must know where life jackets are stowed and how to don them quickly. Regular drills and inspections keep the equipment ready. A life jacket only helps if it is worn; culture and procedure determine whether people put them on in time.

• Personal flotation device for keeping a person afloat
• Designed to support the head and turn the body
• Regulated by safety standards
• Must be accessible and familiar through drills