The first American camouflage systems approved by the
Bureau of War Risk Insurance during the first World War all used some form of
pattern, but it was used in the expectation that it would aid in reducing
visibility at a distance. The desirability of an individual ship was
conceded and the split in policy resulted from the fact that complete
concealment either with pattern or with uniform color, has proved so difficult
of attainment.
The first American camouflaged ship to cross the
Atlantic was the S.S. St. Paul, painted in the winter of 1917 utilizing
"counter-shading" in an effort to reduce visibility of
shadows. This method was based on the research of Abbott H. Thayer a
celebrated American painter of a past generation, who was a pioneer student of
the protective coloration of birds and animals. He was the earliest
advocate of a white ship, and unsuccessfully labored to secure its adoption
both in the U.S. Navy and by the British Admiralty. When, a quarter of a
century later a British artist and naval officer, Lt. Pter Scott, R.N.V.R.,
again proposed the white if very light ship its great value at night or in
overcast weather was beginning to be recognized, and it is now coming into
favor for certain areas. Measure 16, the American equivalent of the
British Western Approaches System, has been named the Thayer System.
In protective Coloration in Nature there is always
some "cover" or fixed background which may be matched. The
background of a ship at sea is constantly changing and the problem is very
much more complex. An inherent difficulty with camouflage for reduced
visibility lies in the fact that the color or shade which is best for one time
will inevitably be the worst possible color at another time. Some
persons have laboriously attempted to average all the possible backgrounds
against which a ship may be seen throughout the day - throughout the
year. Such an average color is merely a "service paint". It is
not camouflage, because it is not aimed at the period of greatest
danger. To have a reasonable chance of success o more limited objective
must be selected.
The requirements of the situation are:
"Pick the particular circumstances under which
a successful camouflage would be of the greatest tactical value. Use
the method of camouflage best suited to accomplish the maximum reduction of
visibility in these circumstances, accepting what increases in visibility
may ensue in other conditions."
Generally speaking light ships are best against
surface observation and dark ships against observation from the air, but it is
necessary to make closer distinctions than we have been in the habit of
doing. The very dark ship will be best at the bombing angle, but at very
long ranges or to low flying planes a lighter ship may be better. For
night or overcast weather the pure white ship will often not be quite white
enough for invisibility, but in bright sunshine it will be extremely visible
when seen sun-down. However, the advent of very light ships is making it
necessary for us to revise the generally accepted dictum that no paint if
effective when the ship is seen up-sun. White or light ships often prove
quite successful when seen up-sun, which in some measure compensates for their
very bad performance when seen down-sun on a bright day.
It is necessary to select the color best suited to
the period of greatest danger, irrespective of high visibility at less
critical times.
In reaching conclusions on systems of camouflage
aimed at surface attack, it is desirable to avoid judgments based on
observations of vessels at close ranges. Except at night or in a thick
fog, no one expects a vessel to disappear at close range, and in clear weather
the color which is deemed satisfactory at that range is almost certain to be
too dark when the vessel begins to reach those ranges where invisibility might
be reasonably expected. Light ships behave better than dark ships at
long ranges, and pure white even in bright sunshine will be better than medium
gray when applied to small area such as masts. In tests made in 1919 on
the U.S.S. Ohio, range finder readings ceased on the masts (painted pure
white) several thousand yards before they stopped on the next ship in the
column where the masts were painted the battleship gray in use at that period.
There is some evidence to show that a vessel
correctly painted to disappear against a horizon sky on a bright day must
inevitably appear very conspicuous when seen close at hand. Invisibility
occurs when a ship presents no contrast with its background, and the customary
approach which has been to match the paint to the sky, can never completely
succeed because it ignores the shaded areas of the ship which we now call
contained shadow.
It is obvious that the invisible ship must be the sum
of two reflectances--that of the contained shadow and that of the
camouflage Paint. Since the shadow is almost invariably much darker than
the sky, it is necessary to make the paint lighter than the sky in order that
the visual mixture of the two, which occurs at a distance, shall exactly equal
the sky background. Large areas of light paint on the superstructure,
appearing as strong contrast close at hand, may well prove to be the only way
by which the shadow can be obliterated.
The situation is quite different when the vessel is
seen from the air against the water. In this case the shadows are not
very different from the color of the water, and the dark colors such as Navy
Blue and Deck Blue will serve to conceal the vessel very effectively.
The menace of air attack caused a general revision of
ideas about camouflage, and complicated the situation for protective
coloration camouflage even more than it did for deceptive camouflage The
very dark ship proved best against aerial observation, and the very light ship
was best from the surface viewpoint. A compromise color was not very
good for either situation. This dilemma has made a deliberate choice
necessary, a choice dictated by the chief source of danger in any given
area. The belief that one average color could serve as a universal
panacea was always untenable, but the advent of aerial attack made it obvious.
An average sky, spoken of as the "weather
coefficient", may be a matter of interest, but it is a matter of no real
importance, unless it can be shown that such an average sky matches the
typical sky of the period of greatest danger. The methods used in
seeking to attain reduced visibility remain much the same as they have always
been, but there is a new understanding of their proper use, which should
insure more effective results. Our use of Measure 21 in Pacific areas,
and the British use of their Western Approaches System in Northern waters, are
good examples of a tactical use of paint whereby high visibility under certain
conditions is accepted as an essential cancomitant of reduced visibility for
more critical periods.