We have it on good authority that the dropping of a canvas bag over U-boat periscopes was among the desperate remedies considered by the British during the early days of World War I.
"I. SSN: The Queen of the Seas?,"
Naval War College Review: Vol. 44:
2, Article 10.
Available at: https://digital-commons.usnwc.edu/nwc-review/vol44/iss2/10