The T11 was an acoustic torpedo
with a highly sophisticated electronic guidance system designed to track ships by the sound of their propellers.
Items include an M4 Enigma Machine (two of these, which enciphered and deciphered the German secret code Enigma, were recovered from U-505), a lead-covered codebook (weighted to sink if thrown overboard), a T5 acoustic torpedo
engineered to home in on a ship's propeller noise (the first of these to be captured by the Allies), an anti-aircraft gun, the sea strainer cover, and a spare piston for the diesel engine (as large as a person).
Silex lifts an acoustic torpedo
and has a range reported to be 30 nautical miles, whereas the SUW-N-1 (formerly designated FRAS-1 by Western Intelligence) fires a nuclear depth charge an estimated 75 km on a ballistic trajectory.
Technically specific electronic equipment, waterborne training, and procedural maintenance are included in implementing three acoustic torpedo test ranges built to US Navy specifications.
A return delegation from the US Navy is required to travel to Brazil to conduct a site visit and finalize the demographic and technical specifications for the installation of the three acoustic torpedo test ranges.
The subs were now also equipped with an acoustic torpedo
that homed in on the sound of a ship's propellers.