I found a great picture that was released from the Navy. The signal flag in the picture is probably a size 14 which is 4′ x 6′.
050811-N-3136P-032 Pacific Ocean (Aug. 11, 2005) – Sailors assigned to the Navigation Department hoist flags to communicate with the guided missile destroyer USS Fitzgerald (DDG 62) from the signal bridge aboard the conventionally-powered aircraft carrier USS Kitty Hawk (CV 63). The Navy’s USS Kitty Hawk Carrier Strike Group, including the embarked air wing The Kitty Hawk Carrier Strike Group is participating in the third annual Joint Air and Sea Exercise (JASEX) with the U.S. Air Force and U.S. Marine Corps in the Western Pacific. JASEX focuses on integrated joint training proficiency in detecting, locating, tracking and engaging units at sea, in the air, and on land, in response to a range of mission areas. U.S. Navy photo by Photographer’s Mate Airman Jimmy C. Pan (RELEASED)
In comparison our flags are 8 x 8″. I have included a picture of our Letter R.
Since signal flags on ships need to be seen from long distances they have to be large. Bring a bit of the ocean by ordering a personalized signal flag banner- IB Designs, USA