Former US Navy Submarine Officer explains why the periscope is raised when submarines dive

‘There are a number of reasons for it… First, because the procedure says it should be,’ David Kirk, former US Navy Submarine Officer.

The periscope is the eye of the submarine. It was invented and developed solely for the purpose of providing a means to view the surface without fear of detection by surface craft.

Why is the periscope raised when submarines dive?

‘There are a number of reasons for it…,’ David Kirk, former US Navy Submarine Officer / Strike Warfare Officer, says on Quora.

‘First, because the procedure says it should be.

‘Now as to why?

• The Officer of the Deck (OOD) is required to continue a visual search of the horizon to ensure no enemy threat aircraft or surface ships detect them until they are submerged.
• The OOD needs to visually verify that the main ballast tanks (MBT) vents properly opened and are venting. If one fails the tank will not properly fill with water and it can affect reserve ballast and also affect further damage control efforts in several casualties. The OOD announces “Venting Forward” then looks aft and reports “Venting Aft”.
• By procedure, The OOD needs to report when the ‘decks are awash’ so the chief of the boat can close the MBT vents.
• By Procedure, the OOD needs to report when the scope’s under so the entire ship’s control party is aware and so the Chief of the Watch (COW) can lower any remaining masts or antennae that the OOD may have wanted raised… Having scope under means the Diving officer of the Watch (DOOW) can use a larger down angle to proceed to depth without fear of the screw coming out of the water.

He continues;

‘Submariners live and die by written procedures. They break them out before every evolution and use them as checklists. In a casualty they perform their immediate actions then breakout the procedures and audit their actions. The OOD does a reread of it before going on watch if he knows he/ she’s expecting to do some procedure – I read the dive or surface procedure before every almost every watch where I was expected to be involved even after years of doing it. The crew, when they’re poking holes in the ocean, before they talk about sports or liberty will break out procedures and train on them. Senior enlisted ensuring junior enlisted are aware of the reasons behind each step and teaching the many pitfalls that happen when procedures aren’t followed verbatim.

‘To give you some insight. If in the middle of doing an evolution you determine the procedure is flawed. You place the ship or the reactor into a safe condition. Stop the procedure, go back to the appropriate officers and chiefs to rewrite the procedure, then train on the procedure, and then attempt the procedure.

‘It sounds insane to most people but to a submariner it is the best way to ensure that a mistake doesn’t occur. Early in the submarine force for the US Navy… Sailors treated submarines like surface ships and relied on tribal knowledge, and the ‘all knowing’ senior NCO’s and often times ships sank next to the pier as things were forgotten or missed. It is much harder to, in procedural error sink a surface ship, because it is never intended to submerge.

‘Between 1905 and 1935 probably 20 or so ships were sunk and raised pier-side. Many times, the crew got off but a few times sailors or officers died. Which is why the submarine warfare patch and later pin was developed to identify those sailors who lived with that extra risk. It grew into a formal qualification program and became emulated by the aviators, spec warfare and eventually even the surface warfare community in the 1970’s.’

He concludes;

‘Procedures don’t replace common sense nor intuition but enhance it by ensuring you are not missing a simple step with grave consequences. Also, the Duty officer, the OOD (Officer of the Deck), the Engineering duty officer or EOOW (Engineering officer of the watch) are the stop gaps to ensure that procedures and contradictory procedures don’t result in damage or loss of life.’

Photo credit: Photographer’s Mate 1st Class Kevin H. Tierney / U.S. Navy