The method of timing a target across the line is absolutely historically accurate. The “stabilized line” feature disappeared on the Standsehrohr wartime attack scopes (big column with seat and pedals), although there is some evidence it may have been retained in some form, as the “Skizzenbuch Band E” sketch for the gyrocompass system shows a socket connection for a stabilized line even during the war. More study required there.
Commanders were provided with MDv 416, which included among many others the following table for estimating speed by this method.
