Here is what the NPS Soldiers & Sailors System has to say on the subject:
Future Sailors' Indices
The NPS and its' CWSS partners are committed to eventually including the names of all Union and Confederate Naval personnel. Given that the records sources for the Navy are not as well organized as the Army records, nor are they micro-filmed, the target date for this is still to be determined. In the meantime, with funding from the Defense Department, NPS has partnered with Howard University to identify African American sailors who served in the Union Navy during the Civil War (see above). The research has resulted in a database of approximately 18,000 African American sailors from various historical Navy documents. These are currently available on our web site with other related features. This project has received grants from the Department of the Defense Legacy Resources Management Program.