Would like more detailed information on the St. Louis which after it was attached and had to return to Cairo, IL for repairs. How were the captains recruited for these gunboats?

My ggggrandfather was the captain of the St. Louis when it was attached at Ft. Donnelson, TN. He stood next to Com. Foote and was killed on 2-14-1862 while he was cap. of St. Louis.

Information would be appreciated.