NATIONAL ENSIGN The following rules govern the display of the national ensign in port and under way. In Port When not under way, commissioned ships display the ensign from the flagstaff at the stern and the union jack from the jackstaff at the bow from 0800 to sunset. In the case of a mastless ship, the ensign will be displayed from the loftiest hoist on board. After entering a foreign port during darkness, a Navy ship briefly displays the ensign from the gaff at first light to establish nationality. Other ships of war present customarily display their ensigns in return. According to SECNAVINST 10520.4, the oldest ship in the Navy, as identified by the Chief of Naval Operations, is to display the first Navy jack, in lieu of the union jack, at the jackstaff. Under Way When flown under way during peacetime, the ensign normally is displayed during daylight from the gaff (or triatic stay in the case of those ships with mast-mounted booms and stays, which would interfere with the hoisting, lowering, or flying of the national ensign) under the following situations unless otherwise directed by the senior officer present: Getting under way or mooring/anchoring Falling in with other ships Cruising near land When engaged in battle When cruising under wartime conditions, it is customary to fly the national ensign continuously at sea, since battle action may be regarded as always imminent. The union jack is not flown under way except in the case to denote a general court-martial or court of inquiry is in session. In that case, it is flown from a signal yardarm. Size of Ensign/Jack for Shipboard Use Table 10-l shows the appropriate size of the ensign and jack to be used aboard your ship. Remember that the union jack must be the same size as the union portion of the ensign being flown from the flagstaff. Shore Display of the National Ensign The national ensign is displayed from 0800 until sunset at all U.S. naval activity headquarters. The following are additional rules that apply to the display of the national ensign: No other flag or pennant will be displayed above or, if on the same level, to the right of the ensign. Table 10-1.—Sizes of Ensigns and Jacks for Shipboard Use LENGTH HOLIDAY DAILY SHIP FLAG JACK S ENSIGN JACK S ENSIGN JACK STAFF STAFF I DIMENSION DIMENSION I DIMENSION DIMENSION Z Z E E Less 100' 10' Jackstaffs with 8 3'6" 1' 10 9/16" 10 2' 4 7/16" (See Note 1) anchor lights 6' 7 3/4" × × × mounted thereon 2' 7 5/16" 4'6" 100'-150' 12' shall be of sufficient height 8 3'6" 1' 10 9/16" 10 2' 4 7/16" (See Note 1) so as to conform × × × to Rules of tbe 6' 7 3/4 2' 7 5/16" 4'6" 151'-200' 15' Road 7 5' 0" 2' 8 l/4" 8 3'6" 1' 10 9/16" × × × × 9' 6" 3' 9 5/8" 6' 7 3/4" 2' 7 15/16" 201'-450' 17' 7 5' 0" 2' 8 l/4” 8 3'6" 1' 10 9/16" × × 9'6" 3' 9 5/8" × 6' 7 3/4" 2' 7 15/16" 451'-UP 22' 5 8' 11 3/8" 4' 9 13/16" 7 5'0" 2' 8 l/4" × × × × 17' 0" 6' 9 5/8" 9'6" 3' 9 5/8" 10-2