Signal flag Alpha Trucker Hat

As a code signal the International maritime signal flag Alpha (or "Alfa", signifying the letter "A") conveys the meaning of "I have a diver down - keep well clear at slow speed", used to indicate that the vessel has limited manoeuverability, and the presence of a diver in the water around the boat. It is used alone in all countries excluding the United States, Canada and sometimes in Italy, but may be used along with the red and white flag, and sometimes the red and white crossed (St Andrews).