WWI Ship Camouflage
twistedsifter.com
twistedsifter.com
"Dazzle's effectiveness is not certain. The British Admiralty concluded it had no effect on submarine attacks, but proved to be a morale boost for crews. It also increased the morale of people not involved in fighting; hundreds of wonderfully coloured ships in dock was nothing ever seen before or since."
(And Tom Körner's excellent book "The Pleasure of Counting" has the math to back it up. He has a knack for explaining.)
He also mentions the benefit of something invisible: In WWII the allies had to relearn the U-Boat lesson. Some people were arguing that the limited planes they have should be used to bomb more German sites, because they rarely spotted an U-Boat. However --- that was part of their effect: They forced the U-Boats to remain submerged for longer. (Those WWII-style U-Boats were essentially unchanged from WWI. Think of them as submergable normal ships, not as modern submarines. Their speed was severely reduced while submerged. The battery technology of the time was crappy and atom-powered submarines were a long way off. Surfaced they were somewhat faster than most merchant ships.)
Of course in WWII the breaking of the Enigma is closely related to the U-Boat war. And it's also in Tom Körner's book. With stories about Turing and Bletchley Park.
Edit: You can also tell an interesting story about Bayesian reasoning from the anecdote that when the aircraft crews reprogrammed the depth-charges to explode not where the U-Boat was most likely to be, but where the expected value of damage was maximized. And that meant closer to the surface: Most submerging U-Boats where already deeper by the time the charge hit, but those that weren't were mostly destroyed.
The end of (http://en.wikipedia.org/wiki/Battle_of_the_Atlantic_(1939%E2...) also has some things to say about convoys.
It's pretty neat
http://www.amazon.co.uk/Three-Corvettes-Nicholas-Monsarrat/d...
From WW2 rather than WW1 - but I don't think the North Atlantic had changed much.
If Silent Hunter III is at all reflective of reality, WWII U-boats didn't use either radar or sonar for torpedo targeting either, though unlike WWI boats they did have the benefit of an analogue targeting computer which took input from the periscopes and UZO ("U-boat targeting optic", the equivalent of a computer-linked periscope for surface attacks).
There were also acoustic torpedoes, and all subs had passive sonar (the one you can listen to, I'm sure it's in SH3). The XXI supposedly had an active sonar for torpedo targeting, but Germany had barely started making them at the end of the war, and again using it is like yelling your position.
http://en.wikipedia.org/wiki/Dazzle_camouflage
(...including the fact that Austria still uses dazzle on speed trap booths to confuse motorists.)