 Complete the following phrase:  Up to August 1914, there were 68 submarine accidents. There were 23 collisions, 7 battery gas explosions, 12 gasoline explosions, and 13 sinkings due to hull openings not being closed. was lost in the English Channel in 1951 due to the snort mast fracturing and in 1963 due to a pipe weld failure during a test dive. Many other scenarios have been proven to be probable causes of sinking, most notably a battery malfunction causing a torpedo to detonate internally, and 