wwll subs 1943

Pre-war,  US submarines' bottoms were painted hull red.    Early-wartime construction was launched in hull red and were painted into black hull bottoms during their post-workup yard availability.  

Later,  US submarine's bottoms were painted in black for delivery

Here's a link for some of the USN sub color schemes during the war - http://www.shipcamouflage.com/submarines.htm .  Late in 1941 or early 1942, the prescribed anti fouling underwater paint for subs was black.  The 1943 paint manual says to use the current anti fouling paints, which would have been black on subs.  Most subs were painted in Measure 9 (all black), Measure 10 (the gray job) or Measure 32/xSS (various shades of gray and black).