Official Service And Medical Records

http://www.history.navy.mil/faqs/faq19-1.htm

The Civil and Old Military Records Branch, National Archives, 700 Pennsylvania Avenue, NW, Washington, DC 20408 (phone 202-357-5444) has custody of records relating to naval officers from 1798 to 1902 and enlisted men from 1798 to 1885.

The National Personnel Records Center, 9700 Page Boulevard, St. Louis, Missouri 63132-5100 has custody of the official individual personnel records of Navy commissioned officers separated after 1902 and Navy enlisted personnel separated after 1885.
Veterans or next of kin of deceased veterans can order copies of their military records directly on line from the The National Personnel Records Center. Veterans are entitled to one set of their medals and awards. To request his medals, a veteran should send in a separate completed Standard Form (SF) 180 to the Bureau of Naval Personnel, Naval Liaison Office, Room 5409, 9700 Page Boulevard, St. Louis, Missouri 63132-5100. Please write "Do not open in mailroom" on the outer envelope

For recently retired personnel for the first fifteen months after discharge, transfer to the fleet reserve, or retirement, any personnel questions should be sent to Commander, Naval Military Personnel Command, Washington, DC 20370, while medical questions should be directed to Commanding Officer, Naval Reserve Personnel Center, New Orleans, Louisiana 70149.

Other helpful source;
" Official Records Union and Confederate Navies in the War of the Rebellion"