Who must wear a life jacket? Any child under the age of six (6) must wear a U.S.C.G. approved flotation device (PFD) while onboard a vessel under 26 feet in length while the vessel is underway. "Underway" is defined as anytime except when the vessel is anchored, moored, made fast to the shore, or aground. Each person operating, riding on, or being towed behind a personal watercraft must wear a U.S.C.G approved personal flotation device (PFD). Inflatable personal flotation devices are prohibited for personal watercraft use. Each person operating or riding a kayak must wear a U.S.C.G approved personal flotation device (PFD).