Where would have been the largest concentration of gunboats during the Civil War? How about the largest concentration of all naval boats, gunboats and support boats combined, ie, gunboats, transports, rams, tugs, ordnance boats, etc?

More to the point, I am trying to answer the question of whether or not there was ever a greater concentration of Naval power during the Civil War than during the Red River Campaign. (I was asked this question the other day, and couldn't answer it.) Does anyone know of any such situation?