The pressure hull construction was HY - 80 alloy steel ( same as larger nuclear powered submarines ) .
The batteries were contained in separate titanium alloy pressure enclosures ( 14 total ) which hung beneath the hull .
The pressure hull construction was HY - 80 alloy steel ( same as larger nuclear powered submarines ) and the batteries were contained in separate titanium alloy pressure enclosures ( 14 total ) which hung beneath the hull .