The 1927 exercises showed that a searchlight's direction could conceal a battle line or expose it to attacking destroyers. A rear ship shining forward could hide the remaining ships from attackers on that side. On another occasion, the fleet appeared silhouetted against its own beams at eight to ten miles, allowing destroyers to estimate its course. Excessive searchlight use also disclosed neighbouring battleship columns, and observations at nine to ten miles helped attackers fix the enemy's position. A beam directed toward an observer could remove the silhouetting effect even without pointing directly at them. These findings informed defence against the night attacks the fleet was practising.
Notable Point · 49:07-51:06
Searchlights can reveal a battle fleet to destroyers
Exercise reports show how searchlight direction could hide ships or disclose their position and course to destroyer attackers miles away.