Let these steps guide your Civil War sailor research.
No matter the side your Civil War sailor ancestor chose, his records won't be equal to soldiers' compiled military service records (CMSR).
For Union sailors, turn to Lewis R. Hammersly's General Register of the United States Navy or Marine Corps, 1792-1892, or Edward W. Callahan's List of Officers of the Navy of the United States and of the Marine Corps from 1775 to 1900. If your ancestor was an enlisted man, get his enlistment date and name of ship in the National Archive and Record Administration's (NARA)Index to Rendezvous Reports, Civil War, 1861-1865 (item T1099). You can then order the Rendezvous Report (similar to enlistment papers) from NARA's Textual Archives Services Division in College Park, MD (301-837-3510). You can access original reports and ship muster rolls at NARA in Washington, DC.
For Union officers, look in the Abstracts of Service Records of Naval Officers, 1798-1893 (film M330) and 1829-1924 (film M1328). If your Union sailor or his family filed for a pension, consult the same sources as for soldiers (see the July 2007 Family Tree Magazine).
Confederate naval records are probably the most challenging, warns NARA librarian Lee D. Bacon. Many didn't survive the war, and those that did were often in poor condition. Sources you can try at NARA include Confederate Naval and Marine Personnel Records (M260) and Subject File of the Confederate States Navy, 1861-1865 (M1091); both are also on Family History Library (FHL) microfilm.
Look for these books at the FHL and other large libraries: Confederate States Navy Research Guide by Thomas Truxton Moebs (Moebs Publishing Co., out of print) and the Office of Naval Records' Register of Officers of the Confederate States (J.M. Carroll & Co., out of print).
Learn more about what your ancestor's ship did in the Naval version of the OR, the 30-volume Official Records of the Union and Confederate Navies in the War of the Rebellion, and the General Index by Dudley W. Knox (Antiquarian Press).