It would be an error to assume anything regarding CS sailor dress. Like their army comrades, what they were provided with varied by time/location/circumstances.
I recall reading about the excavation of the Confederate naval cemetery in Charleston, near a stadium, and the archaeologist reported the buttons o the pants were in a horizontal line (as in drop-front pants vs. a button-fly with them in a vertical row.)
That said, the CS Navy acquired a vast quantity of US Navy clothing at Gosport in 1861, and this was employed for quite a while. In the west, in May, 1861 at New Orleans, the Navy contracted for domestic seaman's clothing (blue flannel shirts, caps, trousers). That same month Navy Secretary Mallory ordered that clothing be procured in England was to be similar to that in use by the Royal Navy, though devoid of insignia. The imported goods were to include;
"For seamen.--Two thousand pairs pants, cloth or cassinette, 2,000 jumpers, 1,000 round jackets, 2,000 pairs duck pants, 2,000 blue flannel overshirts. 2,000 blue flannel undershirts, 2,000 blue flannel drawers, 2,000 pairs of shoes, 3,000 pairs of socks (woolen), 2,000 blankets. 2,000 blue cloth caps, 1,000 pea jackets, 2,000 barnesley shirting frocks, 2,000 black silk handkerchiefs, 1,000 yards of bunting divided into red, white, and blue. (To be similar to the clothing used in the British navy without any designating marks.)"
The blockade made supply tough, and after the fall of Vicksburg a large quantity of cloth and clothing for the Navy which was imported into the Trans-Mississippi West was trapped in that quarter. There is reference that from that point the Navy purchased "plain but substantial clothing" on the open market for the crews of the eastern squadrons...
Jesse Marshall,
Hernando, FL