Step Zero in becoming “Qualified in Submarines” is to become qualified in operating one of these: Submarine Expulsion Toilet
There are eleven valves in this photo. Twelve if you count the two-way rocker valve as two valves. Learn the six or seven that you need to know, and don't touch the other five. Even if you're half asleep in the middle of the night. Bring your reading glasses so you can see the needles and the numbers on the gauges. But don't drop them in the toilet.
Sequence of operation: 1. Check the sea pressure gauge to ensure that you are no deeper than 200 feet (60 m); 2. Inspect the installation to ensure that all six valves are shut; 3. Open the flapper valve at the bottom of the toilet bowl and verify that the expulsion chamber below it is empty. (There may be some residual air pressure in the expulsion chamber, so don’t look too quickly.); 4. Shut the flapper valve; 5. Open the toilet bowl sea valve; 6. Briefly open the toilet bowl stop valve until the water level in the bowl is adequate; 7. Shut the stop valve; 8. Shut the sea valve; 9. Use the toilet; 10. Open the flapper valve to empty the contents of the bowl into the expulsion chamber; 11. Shut the flapper valve; 12. Monitor the pressure gauge on the volume tank and the sea pressure gauge; 13. Deflect the rocker valve to pressurize the volume tank to 10 psi (70 kPa) above sea pressure; 14. Open the gate valve on the discharge line from the expulsion chamber; 15. Open the plug valve on the discharge line from the expulsion chamber; 16. Operate the rocker valve (the other way this time) to blow the contents of the expulsion tank overboard; 17. Shut the plug valve; 18. Shut the gate valve; 19. Repeat steps 3 and 4; 20. Tidy up.
Remember, the goal is not for the ocean to flow in. It's for the shit to flow out. Don't become a member of The Order of the Brown Dolphin.
Photo courtesy Dale J. Brugh