Rear Admiral Henry B. Wilson, Commander, United States Patrol Forces based in France, to Commanding Officers
U.S.NAVAL FORCES OPERATING INEUROPEAN WATERS,
Patrol Squadrons Based on French Coast,
30 January 1918
From: Commander U.S.Naval Forces in France,
To: Commanding Officers.
SUBJECT: Faulty assembling of Mark II depth charges.
1. The following letter from the Commanding Officer U.S.S.MONAGHAN is quoted for information of all concerned:
“On 24 January this vessel expended two mark II depth charges by way of experiment, depth set at 80 feet and only one exploded. Upon careful examination and test it was found that the two remaining depth charges on board; of the same mark could not possibly fire owing to the following condition:- In assembling piece No. 5, (extension for releasing plunger) was not screwed home in its sleeve, leaving too much space between the upper end of piece 11 (releasing plunger) and the lower end of piece 5. The result is that when piece 3 (hydro piston), is flush up against the base of 17, (mechanism casing) there is still about a quarter of an inch between pieces 5 and 11 – this makes it impossible to release the firing pin under any condition.
By threading the upper end of piece 11 and screwing on a piece of pipe – increasing it to the length required [-] the firing pin is properly released.
Since three out of the four depth charges on this vessel required the above alteration it is thought that the condition may be chronic among the mark II type of depth charge, and that the above information may be of value to ships equipped with mark II depth charges.”
Source Note: D, DNA, RG 45, Entry 520, Box 339. Identifying markers “FILE 420” and “HC/(0)” appear across the top of the page. This letter apparently came with a diagram, which has not been found.