I found that when you use the keyboard shortcut 'I' to open/close the 'Torpedo Management' screen, it also open/closes the 'System Management' screen which the keyboard shortcut 'Y' does. Completed first patrol, narrowing missed being sunk by PB Wakatake after sending a Big Old Hansa Freighter into early retirement.
Almost went too deep trying to get away. Suffered some hull damage before my porpoise submarine came back up to a safer depth.