Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, to the Bureau of Ordnance
X-11 IL 9035
<June 5, 1918.>
9035 Available information indicates enemy submarines when attacked dive to depth 150 feet to 300 feet. Interrogation of prisoners develops that effect of depth charge explosion below submarine is much more severe than when explosion taken place above. Recommend immediate provision of increased depth setting up to 300 feet in mark-2 modification-1 depth charge. Consider entirely practicable for destroyers having speed 18 knots or more drop without damage to dropping vessel, depth charges containing explosive charge 600 pounds. Recommend Buord manufacture depth charges containing such explosive charge sufficient quantity to permit xxxxx issue four these charges to each destroyer. These charges to be issued in addition to present type. Letter follows. 07205. 9035.
Buord 720 am 6-5-18
Source Note: Cy, DNA, RG 45, Entry 517B.