The Dangers Within
U-boats were full of top-secret information and technology that Germany hoped would never fall into Allied hands. U-boat captains were under strict orders to scuttle (sink) their own subs if they were in danger of capture.
The U-505 sailors attempted to scuttle their boat by flooding it. They opened a pipe, called a sea strainer, which caused water to rush into the boat. By the time the boarding party arrived, the sub's stern was submerged and the ocean waterline almost reached the top of the conning tower. When Motor Machinist's Mate 1st Class Zenon Lukosius came aboard, he saw water pouring in through the sea strainer, immediately searched for the strainer cover and re-secured it.
Before abandoning the U-505, the German crew was also trained to set the timers on numerous scuttle charges, or time bombs, located throughout the sub. The boarding and salvage parties quickly yanked the wires on the charges they discovered. If just one of the devices had detonated, it could have sent the U-boat and the American sailors to the bottom.