I recently had the opportunity to answer another Quora question relating to submarines; How does a submarine deal with a hovering enemy helicopter that may drop a depth charge? This was another fun question to answer, and gave me a bit of opportunity to reminisce on my submarine service.
On my first submarine USS Scamp I had the advantage of always being in the middle of our underway operations. For the first two years onboard I worked as an Electronic Surveillance Measures (ESM) operator. My watch position involved searching for and analyzing electronic signals, mostly radar, while we were at periscope depth. In this position I worked closely with the Sonar Operators (fondly nicknamed “Sonar Girls”), who always seem to be heroes in submarine movies.
For the next two years I stood Quartermaster watches, responsible for maintaining navigation of the boat. Navigation is pretty important for any ship out in open ocean, especially when the ship’s crew can’t see where they’re going. Both watch positions put me in the control room where I was able to witness everything we did.
My Quora answer to “How does a submarine deal with a hovering enemy helicopter that may drop a depth charge?”
It tries to get away from the area. Fast.
The one vulnerability submarines have is against aircraft, particularly helicopters fitted out for Anti-Submarine Warfare (ASW). It’s not just the helo that’s a threat, it’s when there are two or more helos working an area backed by their surface platforms. Helos in open waters will always be supported by a surface platform – their airport – as helos have relatively limited range compared to fixed wing aircraft.
With two or more helos using their dipping sonars (basically hydrophones on the end of a long cable dangling from the helo) sending their data back to a surface ship who’s also listening or actively pinging, the data can be combined into a fairly accurate picture of where the sub is located and which direction she’s headed. This provides adequate targeting information for a weapons release.
Subs do not carry any anti-aircraft weapons. Nuclear subs have the advantage of high underwater speed, unlimited range, and relatively deep diving, so if a sub is caught in a helo/surface ship net the best defense is to high-speed get away from there and try an approach later. If it’s a diesel sub, then they’re going to have problems as their underwater speed and range is severely limited.
On my first submarine, a nuclear fast-attack, we spent a lot of time working with our surface fleet performing ASW training, also called “screen-penetration exercises.” As the sub, our goal was to get close enough to the surface ships to take close-up periscope photos and launch signal flares while submerged, letting the surface ships know we “got them.” The signal flares represented weapons we could have launched had it been a shooting war. The photos were proof they didn’t know we were around and we were close.
The surface ship’s mission was to keep us from getting close, and chase us off if they found us. Their signaling method to the sub was to drop “Practice Depth Charges” (PDC) which are small underwater explosives about the size of a hand grenade. Too small to do any damage to a sub, but they make enough noise to let the sub know they were attacked.
Most of the time during these exercises any PDCs were typically dropped a long ways away from us, if they were dropped at all. Only one time did we have a close encounter, when we were attempting to get past a screen of three destroyers with three ASW helos out looking for us. They actually had us pinned down at one point and dropped a PDC that exploded close enough to knock some paint off our outer hull.
But that was only once in about eighteen months of near-continuous screen-penetration exercises, so I’d say the advantage is still with the sub.Quora Answer
As of today, October 18, my answer has 18.3K views and 167 upvotes. Nowhere near as many as my all-time most popular answer to “What is something nobody knows about submarines?” But this is still good.