Smoke would be a waste of time in AH...icons dontcha know 
True we have icons, but a lot of PTs get wacked before they get into icon range by 5 inchers. A PT or two out in the lead with a smoke screen hides the guys coming up behind them.
A smoke screen around your CV hides it from shore batteries and makes it more difficult for bombers to see you turning.
A smoke screen also hides the spawning boats from aircraft unless the aircraft want to come down low to the water and be in AAA range.