Tis hard to understand that a vessel which never returns to homeport as it left, can be called successful.

We had some saying in the Submarine force, a successful dive ends in surfacing, or something very similar.

WORLD SUBMARINE HISTORY TIMELINE
PART ONE: 1580-1869

Prepared for NOVA by Captain Brayton Harris, USN (Retired)
Author, The Navy Times Book of Submarines: A Political, Social and Military History
http://www.submarine-history.com/NOVAone.htm

Re The Hunley

"This submarine was sent to Charleston, to try to break the Federal blockade. Almost immediately, it, too, sank -- possibly twice, swamped by the wake of a passing steamer, with the loss of some crewmembers. Confederate Commanding General P. G. T. Beauregard became disenchanted but Horace Hunley persuaded him to allow "one more try" under his -- Hunley's -- personal supervision. The boat sank again, killing Hunley and the crew.

It was found, and raised -- and two members of the original team who had not been aboard harassed Beauregard often enough that , after "many refusals and much discussion," he agreed to allow one more attempt -- but not as a submarine. The boat -- now named CSS H. L. Hunley in honor of her spiritual father -- was to be armed with a spar torpedo and operate awash, as a David."
http://www.submarine-history.com/NOVAone.htm