At the time of the Star of the West only the Morris Island battery and Fort Moultrie was complete enough to fire at that ship. Fort Johnson batteries were still under construction. The Morris Island battery that fired at the Star of the West was masked from Fort Sumter by sand dunes and could not fire in that direction. Fort Moultrie never got the range of the Star of the West and was in fact out of range of those particular guns. Once past the Morris Island guns the Star of the West need only put Fort Sumter between it and Fort Moultrie, if the water was deep enough. Once the ship was in place it would be only moments to discharge the troops, each carrying forty pounds of supplies. But that plan was extremely faulty even if they succeeded; they would only have to repeat it every couple of weeks, or take out Fort Moultrie immediately after reenforcement.
______________________
David Upton