Summary: A military training film showing how the inclination and speed of a sea-borne target is judged then converted into travel corrections and how to observe the fall of shot and correctly fire onto the target.
Description: (Reel 1) Part 1: Inclination and Speed: humorous portrayal of an eighteenth century naval cannon firing half of commander's moustache off; cut to 1940's coastal command post. Diagrammatic explanation of travel connections needed to hit moving target. Line correction and range correction equal travel corrections and are dependent on two things - course of target and speed. Use of rangefinder, diagrams of inclination through angles from target and identifying the wash to establish the course of the target including a test to work out the angle of movement of the target. How to ascertain speed of various craft in rough/calm sea through size of bow wave and wash ie 15 knots - bow wave large, wash small; 30 knots - bow wave smaller and wash larger. Practical application of speed and inclination principles using DRF (depression range finder) to follow target and make corrections; emphasising importance of practice; what to do in an emergency situation. (Reel 2) Part 2: Observation of Fire: Diagram of view through binoculars marked at one degree grades to work out the error of line; calculating range via position of splashes, either behind or in front of target and correct accordingly; zones of dispersion include 100% zone where rounds of ammunition fall in relation to ammunition and meteorological quirks, 500% zone - falls in centre, MPI - mean point of impact. For error calculation see Coastal Artillery Training Manual Volume 1, page 81; angle of arrival and calculation of plus or minus error to hit target; type of ship can alter plus or minus calculations therefore each BOP (battery observation point) has a table of corrections. (Reel 3) Avoidance of too much smoke from minus rounds blocking view; shooting at night; identification and correction of rounds through shape of splashes; extensive use of diagrams. Dramatised account of incorrect way to calculate travel corrections followed by correct way and the blowing up of a U-boat.
