Why Black Boats Got the Blues?

March 27, 2006: The Royal Navy, after extensive research, has concluded that submarines should be painted a shade of deep blue, rather than black, to protect them from detection while surfaced. Subs have been painted black, or some form of camouflage pattern, for over a century. But, as with many other color schemes in the past, close examination usually reveals ways to do it.

Actually, the paint job on a submarine has very little to do with its chances of being spotted. Nuclear subs (Britain only has nuclear subs) are under water nearly all the time they are at work. The only time they surface is, sometimes, when sending commandos ashore, or picking them up. Many subs can do this while still submerged. These command operations usually take place at night, when black paint does the concealment job quite well. What the British camouflage experts discovered was that, during the day, or in overcast weather, black was much less effective at concealing a surfaced sub than was the new shade of dark blue.

Even diesel-electric subs, which spend most of their time on, or near, the surface, don't depend all that much on their paint job. Radar and sonar are more likely, than an eyeball, to detect a surfaced sub. Not only that, most diesel-electric subs have a schnorkel device, which enables the sub to stay beneath the surface, with only the washing machine sized schnorkel be above the water, to get air into the sub, for the crew and its diesel engines.

The new color does provide better concealment in tropical waters, that are "brighter" than the cooler north Atlantic and Arctic waters that have been the scene of most submarine operations over the past century. Currently, subs are more likely to be roaming warmer waters.

If anything, the new British innovations hurts them, more than it helps them. Navies that have lots of diesel-electric boats will now repaint them this more effective color, making it more difficult for the British to detect them.

http://www.strategypage.com/htmw/htsub/articles/20060327.aspx