The U.S. Navy officer rank insignia reference article from the English Wikipedia on 24-Apr-2004
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U.S. Navy officer rank insignia

Sponsorship the way you would do it
Collar
devices 		Dress uniform
Shoulder Sleeve
Fleet Admiral
O-11
(wartime only) 		O-11 collar insignia O-11 shoulder insignia O-11 sleeve insignia
Admiral
O-10 		O-10 collar insignia O-10 shoulder insignia O-10 sleeve insignia
Vice Admiral
O-9 		O-9 collar insignia O-9 shoulder insignia O-9 sleeve insignia
Rear Admiral
(upper half)
O-8 		O-8 collar insignia O-8 shoulder insignia O-8 sleeve insignia
Rear Admiral
(lower half)
O-7 		O-7 collar insignia O-7 shoulder insignia O-7 sleeve insignia
Captain
O-6 		O-6 collar insignia O-6 shoulder insignia O-6 sleeve insignia
Commander
O-5 		O-5 collar insignia O-5 shoulder insignia O-5 sleeve insignia
Lieutenant
Commander
O-4 		O-4 collar insignia O-4 shoulder insignia O-4 sleeve insignia
Lieutenant
O-3 		O-3 collar insignia O-3 shoulder insignia O-3 sleeve insignia
Lieutenant,
Junior Grade
O-2 		O-2 collar insignia O-2 shoulder insignia O-2 sleeve insignia
Ensign
O-1 		O-1 collar insignia O-1 shoulder insignia O-1 sleeve insignia

This chart represents the U.S. Navy officer rank insignia.

Other U.S. armed
forces insignia
Army enlisted
Army officer
Navy enlisted
Navy officer
Air Force enlisted
Air Force officer
Marine Corps enlisted
Marine Corps officer 




The most junior ensign onboard ship receives an enlarged collar device insignia that must be worn.  This officer is the "butterbars" for the voyage and, by tradition, receives an undue amount of grief from fellow officers.