The U.S. national ensign, sometimes called "50-star" or "Old Glory," is the proper and preferred flag for all U.S. vessels. Your boat should wear it from 0800 until sunset, and when you enter or leave port during daylight or at night, weather and rig permitting. While in port, if you leave your boat and will not return before sunset, lower and stow the national ensign before you go.
The national ensign worn by a vessel must be the flag of her registry?not necessarily that of the owner or operator.
Generally, the national ensign should be displayed at the peak of the gaff, i.e., the outer end of the spar extending aft from the mast of your boat?if you boat has a gaff. If it does not, fly it from the flagstaff at your boat's stern. If your boat has an overhanging boom or an outboard motor, your flagstaff may be offset to starboard (preferably) from your boat's centerline.
On a sportfishing boat, where a stern staff might interfere with the gear, and vice versa, the practice is to fly the ensign from a halyard rigged amidships on the after part of the superstructure.
Marconi-rigged sailboats may fly the ensign from the leech of the aftermost sail (or from the back stay), approximately 2/3 the distance up its length. This puts it in about the same position it would occupy if the boat were gaff-rigged.
At anchor or made fast, the ensign should be flown from the stern staff of all boats. The U.S. national ensign has a 10:19 hoist/fly ratio.
