Τρίτη, 31 Μαΐου 2016

Didn’t know how they worked, until now: Dazzle ships, to confuse the U-Boat range finders

 


Nature always knows best.
That dazzle did indeed work along these lines is suggested by the testimony of a U-boat captain:
It was not until she was within half a mile that I could make out she was one ship [not several] steering a course at right angles, crossing from starboard to port. The dark painted stripes on her after part made her stern appear her bow, and a broad cut of green paint amidships looks like a patch of water. The weather was bright and visibility good; this was the best camouflage I have ever seen
U-boats were equipped with two periscopes, one for searching out enemy ships, the other with a more powerful lens but narrower field of vision for use in combat. Though the use of periscopes allowed the U-boat to remain safely underwater while carrying out an attack, looking straight out at misty sea level, which was rarely level at all made accurate vision very difficult. Hitting anything with a torpedo this way is as much a testament to luck as it is to skill.
Wilkinson advocated "masses of strongly contrasted colour" to confuse the enemy about a ship's heading.
Wilkinson advocated “masses of strongly contrasted colour” to confuse the enemy about a ship’s heading.
Even so there were those among the allies who thought they knew how to shift the odds even further. Naval ships were already being painted gray to blend in between the ocean and sky as much as possible. But a ship at sea cannot really be camouflaged as colors change along with the light throughout the day and when silhouetted against a blank horizon it is impossible to hide. But since ships were almost always moving targets U-boat commanders had to aim their torpedos at where they thought the ship would be when it reached it, not at the point where the ship was seen. This involved careful calculation of distance, heading, and speed based on the coincidence principal, and this is where Norman Wilkinson thought they could be deceived.

While dazzle, in some lighting conditions or at close ranges, might actually increase a ship's visibility, the conspicuous patterns would obscure the outlines of the ship's hull (though admittedly not the superstructure), disguising the ship's correct heading and making it harder to hit.
While dazzle, in some lighting conditions or at close ranges, might actually increase a ship’s visibility, the conspicuous patterns would obscure the outlines of the ship’s hull (though admittedly not the superstructure), disguising the ship’s correct heading and making it harder to hit.
Unlike other forms of camouflage, the intention of dazzle is not to conceal but to make it difficult to estimate a target’s range, speed, and heading. Norman Wilkinson explained in 1919 that he had intended dazzle more to mislead the enemy about a ship’s course and so to take up a poor firing position, than actually to cause the enemy to miss his shot when firing.
Dazzle was adopted by the Admiralty in Britain, and then by the United States Navy, with little evaluation. Each ship’s dazzle pattern was unique to avoid making classes of ships instantly recognisable to the enemy. The result was that a profusion of dazzle schemes were tried, and the evidence for their success was at best mixed. So many factors were involved that it was impossible to determine which were important, and whether any of the colour schemes were effective.
Dazzle was created in response to an extreme need, and hosted by an organisation, the Admiralty, which had already rejected an approach supported by scientific theory: Kerr's proposal to use "parti-colouring" based on the known camouflage methods of disruptive coloration and countershading.
Dazzle was created in response to an extreme need, and hosted by an organisation, the Admiralty, which had already rejected an approach supported by scientific theory: Kerr’s proposal to use “parti-colouring” based on the known camouflage methods of disruptive coloration and countershading.

Kerr's explanations of the principles were clear, logical, and based on years of study, while Wilkinson's were simple and inspirational, based on an artist's perception
Kerr’s explanations of the principles were clear, logical, and based on years of study, while Wilkinson’s were simple and inspirational, based on an artist’s perception
Dazzle attracted the notice of artists such as Picasso, who claimed that Cubists like himself had invented it.Edward Wadsworth, who supervised the camouflaging of over 2,000 ships during the First World War, painted a series of canvases of dazzle ships after the war, based on his wartime work. Arthur Lismer similarly painted a series of dazzle ship canvases.
Now this demonstrates it perfectly - Claimed effectiveness: Artist's conception of a U-boat commander's periscope view of a merchant ship in dazzle camouflage (left) and the same ship uncamouflaged (right), Encyclopædia Britannica, 1922. The conspicuous markings obscure the ship's heading.
Now this demonstrates it perfectly – Claimed effectiveness: Artist’s conception of a U-boat commander’s periscope view of a merchant ship in dazzle camouflage (left) and the same ship uncamouflaged (right), Encyclopædia Britannica, 1922. The conspicuous markings obscure the ship’s heading.
At first glance, dazzle seems an unlikely form of camouflage, drawing attention to the ship rather than hiding it. The approach was developed after Allied navies were unable to develop effective means to hide ships in all weather conditions. The British zoologist John Graham Kerr proposed the application of camouflage to British warships in the First World War, outlining what he believed to be the applicable principle, disruptive camouflage, in a letter to Winston Churchill in 1914 explaining the goal was to confuse, not to conceal, by disrupting a ship’s outline. Kerr compared the effect to that created by the patterns on a series of land animals, the giraffe, zebra and jaguar.

SHARES
The American data were analysed by Harold Van Buskirk in 1919. About 1256 ships were painted in dazzle between 1 March 1918 and the end of the war on 11 November that year. Among American merchantmen 2500 tons and over, 78 uncamouflaged ships were sunk, and only 18 camouflaged ships; out of these 18, 11 were sunk by torpedoes, 4 in collisions and 3 by mines. No US Navy ships (all camouflaged) were sunk in the period
The American data were analysed by Harold Van Buskirk in 1919. About 1256 ships were painted in dazzle between 1 March 1918 and the end of the war on 11 November that year. Among American merchantmen 2500 tons and over, 78 uncamouflaged ships were sunk, and only 18 camouflaged ships; out of these 18, 11 were sunk by torpedoes, 4 in collisions and 3 by mines. No US Navy ships (all camouflaged) were sunk in the period

1417729_537468716336813_243128434_o (1)
Taking up the zebra example, Kerr proposed that the vertical lines of ships’ masts be disrupted with irregular white bands. Hiding these would make ships less conspicuous, and would “greatly increase the difficulty of accurate range finding”. However, in the same letter, Kerr also calls for countershading, the use of paint to obliterate self-shading and thus to flatten out the appearance of solid, recognisable shapes. For example, he proposes to paint ships’ guns grey on top, grading to white below, so the guns would disappear against a grey background. Similarly, he advised painting shaded parts of the ship white, and brightly lit parts in grey, again with smooth grading between them, making shapes and structures invisible.
What Wilkinson wanted to do was to make it difficult for an enemy to estimate a ship's type, size, speed, and heading, and thereby confuse enemy ship commanders into taking mistaken or poor firing positions
What Wilkinson wanted to do was to make it difficult for an enemy to estimate a ship’s type, size, speed, and heading, and thereby confuse enemy ship commanders into taking mistaken or poor firing positions
Kerr was thus hoping to achieve both a measure of invisibility and a degree of confusion for the enemy using a rangefinder. Whether through this mixing of goals, or the Admiralty’s skepticism about “any theory based upon the analogy of animals”, the Admiralty claimed in July 1915 to have conducted “various trials” and decided to paint its ships in monotone grey, not adopting any of Kerr’s suggestions. It had made up its mind, and all Kerr’s subsequent letters achieved nothing.
The American artist Abbott Handerson Thayer had developed a theory of camouflage based on countershading and disruptive coloration, which he had published in the controversial 1909 book Concealing-Coloration in the Animal Kingdom. Seeing the opportunity to put his theory into service, Thayer wrote to Churchill in February 1915, proposing to camouflage submarines by countershading them like fish such as mackerel, and advocating painting ships white to make them invisible. His ideas were considered by the Admiralty, but rejected along with Kerr’s proposals as being “freak methods of painting ships … of academic interest but not of practical advantage”.
Depiction of how Norman Wilkinson intended dazzle camouflage to cause the enemy to take up poor firing positions
Depiction of how Norman Wilkinson intended dazzle camouflage to cause the enemy to take up poor firing positions

Eyepiece image of a naval rangefinder, image halves not yet adjusted for range. The target's masts are especially useful for rangefinding, so Kerr proposed disrupting these with white bands
Eyepiece image of a naval rangefinder, image halves not yet adjusted for range. The target’s masts are especially useful for rangefinding, so Kerr proposed disrupting these with white bands
The Admiralty noted that the required camouflage would vary depending on the light, the changing colours of sea and sky, the time of day, and the angle of the sun. Thayer made repeated and desperate efforts to persuade the authorities, and in November 1915 travelled to England where he gave demonstrations of his theory around the country. He had a warm welcome from Kerr in Glasgow, and was so enthused by this show of support that he avoided meeting the War Office, who he had been intending to win over, and instead sailed home, continuing to write ineffective letters to the British and American authorities.
HMT Olympic, RMS Titanic's sister ship, in dazzle camouflage while in service as a World War I troopship, from September 1915
HMT Olympic, RMS Titanic’s sister ship, in dazzle camouflage while in service as a World War I troopship, from September 1915

Wilkinson advocated "masses of strongly contrasted colour" to confuse the enemy about a ship's heading
Wilkinson advocated “masses of strongly contrasted colour” to confuse the enemy about a ship’s heading
The marine artist and Royal Naval Volunteer Reserve officer Norman Wilkinson, agreed with Kerr that dazzle’s aim was confusion rather than concealment, but disagreed about the type of confusion to be sown in the enemy’s mind. What Wilkinson wanted to do was to make it difficult for an enemy to estimate a ship’s type, size, speed, and heading, and thereby confuse enemy ship commanders into taking mistaken or poor firing positions.An observer would find it difficult to know exactly whether the stern or the bow was in view; and it would be correspondingly difficult to estimate whether the observed vessel was moving towards or away from the observer’s position.
dazzle10.jpg
Source wiki / metropostcard

Δεν υπάρχουν σχόλια:

Δημοσίευση σχολίου