Torpedo Deflection Sight Mark VI

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T.D.S. Mark VI[1]

The Torpedo Deflection Sight Mark VI was a simple British torpedo deflection sight. Designed by Defiance, this was to be an emergency sight for fixed above-water tubes on capital ships, but apparently not to be fitted on the tubes themselves.

T.D.S. Mark VI[2]
As simplified in 1921 for C.M.B. testing


A Base plate
B 80 degree slot
C Quadrant
D Pivot
D1 Gyro angle scale
E Raised arc
F Rear sight
G, G1 Limit stops
H Deflection strip
K Sliding block
M Spring plunger
N Limit clamps
P Rear sight clamp
Q Radiomir fore sight
R, R1 Clear range indicators
X Director angle pointer
Y Guide bolt
Z Gyro angle pointer

The whole sight was made so it could hinge down when out of use, and the sturdiness of the design was a point of pride. The gyro angle in use, and the resulting director angle were read off the same scale, up to 40 degrees to either side. The quadrant could rotate on the base plate to set a gyro angle, and a spring plunger could click it into any angle at 5 degree increments. Limit stops permitted easy use of a fixed night firing deflection, and 2 arms (one in line with the torpedo and one able to swing) offered the function of a clear range indicator.

The deflection strip was double-sided, with markings for 29 knot and 35 knot speed settings on the back.[4] A sliding selector block as on other deflection sights permitted one of several speeds on either side of the strip to be highlighted for use by covering the others.

The device would be used as follows:[5]

  1. move sliding block K to proper speed setting
  2. move rear sight to proper deflection and clamp in place (director angle now visible at pointer X)
  3. withdraw spring plunger and rotate quadrant to bring sights on (gyro angle now visible at pointer Z)

In practice, a suitable gyro angle would be placed on the torpedo, and the quadrant locked into this position using the spring plunger. The function of the clear range indicator pieces would be independent of the sight's core function.


By mid-1919, however, no approval had been given to manufacture the sights. The sight could hinged down, and was suitable for use out a narrow opening, as its foresight was on the pivot.[6]

By 1921, two had been manufactured and issued to C.M.B. Base, Haslar for trials in Coastal Motor Boats. These apparently lacked the Clear Range Indicator shown in the 1918 concept drawings.[7]

See Also


  1. Annual Report of the Torpedo School, 1918. Plate 114.
  2. Annual Report of the Torpedo School, 1920. Plate 29.
  3. Annual Report of the Torpedo School, 1918, p. 159.
  4. This mention is curious to me, as the image shows these markings, leaving some doubt as to the speed setting(s) on the "front side".
  5. Annual Report of the Torpedo School, 1918, pp. 159-160.
  6. Annual Report of the Torpedo School, 1918, p. 159.
  7. Annual Report of the Torpedo School, 1921. p. 138.