The Secretary of the Navy shall prescribe a suitable pennant to be known as the Navy Reserve yacht pennant. This pennant may be flown by a yacht or similar vessel if—

((1)) the vessel is documented under the laws of the United States;

((2)) the vessel has been designated by the Secretary, under such regulations as he prescribes, as suitable for service as a naval auxiliary in time of war; and

((3)) the captain or owner of the vessel is a member of the Navy.