Hello- Terry, the scant reference on my shelf to the operational usage of the 'Alligator' comes from Burke Davis.
I am waiting for more reference material at present. According to Davis the 'Alligator' did no more than 'poke about on the bottom' in the Roads.
The 'Alligator' is significant to me on the technological timeline for the fact that de Villeroi considered the use of air conditioning, the removal of Carbon Dioxide and Humidity, of the air contained in the hull while submerged.
A submerged time of three hours was claimed, the record of the crew of the CSS Hunley was two hours and twenty minutes. This time achieved while all were sitting quietly on the bottom.

Hank