In 1973, the naval museum curator Robert F. Sumrall (following Kerr) suggested a mechanism by which dazzle camouflage may have sown the kind of confusion that Wilkinson had intended for it. Coincidence rangefinders used for naval artillery had an optical mechanism, operated by a human to compute the range. The operator adjusted the mechanism until the two half-images of the target lined up in a complete picture. Dazzle, Sumrall argued, was intended to make that hard, as clashing patterns looked abnormal even when the two halves were aligned, something that became more important when submarine periscopes included such rangefinders. Patterns sometimes also included a false bow wave to make it difficult for an enemy to estimate the ship's speed.
