I think both of these apparently newest versions in the Corp. Canvas Series are now currently available, and apparently in each variation as to size and hardware finish
http://haveston.com/hav918c.html
http://haveston.com/hav942c.html
http://haveston.com/havlss-copy.html
Apparently the "ForeCastle" naval grey color was also used for U.S. Navy standard commissioned officer work uniform from 1943 because it was deemed better than the light tan khaki for working around heavy equipment, machinery, weaponry, and even the early analog fire control computers on the ships by that time.
Perhaps based on experiences during the heavy surface warfare in the first months and years of the Pacific War, the color was also apparently considered more appropriate at the command level for making officers less conspicuous to address concern that Japanese aviators would focus their strafing fire on the light khaki clad officers who stood out against the grey super structures of the ships and could also be more easily differentiated from the enlisted ranks as priority targets.
However, the color was apparently reverted to only being an optional alternative to the light khaki officer's work uniform fairly shortly after its initiation and was completely phased out even as an option by 1948.