Ship Camouflage Instructions
United States Navy
Ships - 2 
Revision 2
Bureau of Ships
June 1942

Camouflage Painting Measures

Measure 16 - Thayer System.

Effectiveness.

Lowest visibility to surface observers on moonless nights and in overcast weather. 

High visibility down-sun or down-moon in bright clear weather, but reduced visibility up-sun and up-moon in all weathers.

Especially well adapted for winter use in Northern areas where nights and long and days are frequently overcast.  It would prove useful against submarines in any area where attacks occur mostly at night, but in bright weather it would be very visible to surface raiders, or to high-flying aircraft, when observed down-sun.

Some deception as to target has been reported for both day and night operations.

Special Characteristics.

The special feature of this system is its changeable character.  At low level of illumination a blue paint will appear relatively lighter and a red paint will appear relatively darker than these two paints appear in daylight.  This visual change, known as the Purkinje effect, is utilized in the Thayer System.  The pure light blue which is employed has been selected because it will appear practically like white paint at low levels of illumination.  The ship will therefore appear like a white ship on moonless nights or during twilight when white or very light ships are best for reduced visibility.  During daylight hours or under bright moonlight the pattern will appear and will produce some deception in the estimation of the target angle.  A darker blue would produce more deception but can not be used because it will not appear white at night.  The purity of the color is an important factor in the Purkinje effect, and even a slight admixture of black in the paint will reduce its effectiveness at night.

Colors Employed.

Thayer Blue 5-B
White 5-U

Type Plans.

Typical deception patterns of the Thayer System are shown on PLATES IV to XII inclusive.  Patterns are shown for both port and starboard sides, and should be so used iin order to get the best end-on effects.  Though shown for certain specific classes of ships, the designs can and should be adapted to other types and classes.

The application of similar patterns to both large and small vessels of similar profiles may cause uncertainty as to the identity of the class of vessel.  

A distinctive individual design for each vessel might serve to identify the ship.

Method of Application.

Size of Pattern

In adapting plans to vessels for which they were not specifically designed the size of the pattern should be considered.  As currently practiced in the Fleet, the areas used in pattern camouflage have often been too small to be effective.  Small areas will, beyond a short range, appear as a uniform color, and will have no superiority over such a color.

Countershading

The aim of the Thayer System is to create a ship which will appear like a white ship at night, and the "contained shadow" which is one of the stumbling blocks to all successful camouflage, is far more noticeable on light ships than dark ships.  The situation can be improved by a liberal application of white paint to all areas which are commonly in shadow.  For example the shadow which is usually noticed below and around a small boat can often be lightened by the use of white paint.  The application of white paint to the under side of projecting decks will, through reflection, lighten the vertical surfaces on which they cast shadows.

A pronounced shadow is frequently seen on the bow of some types of vessels due to the bow flare, and a large area of white  applied to the bow, and intended to compensate for this shadow, is a rather common feature of camouflage design.  The importance of countershading at this particular point may be easily exaggerated.  The Thayer System is designed for use in northern latitudes, where due to the low altitude of the sun, the bow flare will present no problem at all during the winter, and will only be noticeable for a few hours in the middle of the day in midsummer.  If a better deception can be secured by the use of blue pattern at this point on the bow, its use would be amply justified.

Countershading with white paint must be left to some extent to individual judgment.  The type plans show only the larger areas of blue pattern, and it may often happen that areas will be found within them which will be improved by countershading with white.

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