Flag C Charlie Size 0 12 X 15 Affirmative H & G The Charlie C flag is 12″ by 12″ (size 0) nylon with heading and grommets. Marine Signal Flag: Letter “C” (Charlie) International maritime signal message: “Yes” or “Affirmative” Marine signal flags are international signals used by ships at sea to spell out short messages, or more commonly, used individually or in combination they have special meanings.