The Hoover and "Analogous Response"

For some reason that I've long since forgotten, there was some brouhaha between the US and the USSR in the late 1970s/early 1980s over the placement of nuclear missiles. The Soviets moved their ICBM patrols into the western Atlantic. That would have given them the ability to make a depressed-trajectory shot, which would have really cut the reaction time available to the Americans.

Needless to say, the Americans were not happy with that. Among other things, TACTASS-equipped ships were sent out to search for and track the Soviet submarines. This operation, in part, took place in the winter.

One does not have to be a naval expert to know that during the winter, the North Atlantic is a challenging place to be.

TACTASS, designated the AN/SQR-18A, attached to the back of the fish of an AN/SQS-35 variable depth sonar (VDS). This is a photo of an apparently Japanese setup:

The fish itself was well-weighted by a goodly amount of lead. The red arrow points to where the towed array was attached. What would happen is the array would be payed out from a reel in a room next to where the VDS fish was housed. The array would then be mated both mechanically and electrically to the VDS fish. Then the fish would be launched. In moderate to heavy seas, this was a wet operation. The side doors, at least, were operated by hydraulics. The crane and cable reel had an operator's station with a waterproof door. Once the array was mated, everyone would leave the room, except for the operator, and the fish would be launched.

As you can see here, the cable between the ship and the VDS fish was faired, with aluminum leading edges and rubber trailing edges:

So now picture that you have a heavy fish being towed by a long cable, which had no elasticity. In a heavy sea, the stern of the ship moved up and down a lot, which jerked on the fish. The cable wouldn't break, but the electrical connections were not as durable, especially the connections between the fish and the array, which itself was several hundred feet long and streamed behind the fish. A fair number of the tracking missions ended with the ship returning to port to replace the towed array, which was shipped on a large cable reel.

Because the weather was often bad enough to preclude the ships from launching their SH-2Fs to localize any contacts, S-3s were sent out to do that work. I don't recall whether or not they flew out from Norfolk and Mayport or if they staged out of NAS Bermuda.

So there was a ship out doing that, and there was a S-3 that was sent out to do its thing. The S-3 told the ship (over secure voice radio) that there was an unknown error in its internal nav system. The ship's ASW officer, who was on watch, asked how large the error was. He was told that it was about a dozen miles or so. The ASW officer advised the S-3 to "mark on top" (fly directly over the ship) and the ship could give them an accurate position so the S-3 could update its navigation picture and thereby greatly reduce the error.

The S-3 refused to do that. They then asked the ship where they should being dropping sonobouys and in what pattern. The ASW officer replied on the order of "I won't know within a hundred square miles of ocean where those buoys are, so it makes no difference to me where you drop them." (The ship was operating on an EMCON [emissions control] plan and it could not use its air-search radar to track the S-3.)

And that was pretty much it. For the rest of the time the S-3 was on station, it flew around, doing something that generated no useful information. When it either ran low on fuel or used up its sonobuoys, it returned to base.

On that ship, the ASW officer wrote the post-patrol report, which was sent off as a radio TTY message. The draft of the report (and all other radio messages) typically was written by hand on a yellow legal pad, either double or triple-spaced. The Weapons and Operations officers reviewed the draft and edited it before it was sent to the CO for his review and approval. This time around, the Captain noticed that the draft was written in the hand of the Weapons officer. When the CO asked why that was so, the Weapons officer said that the ASWO wanted to re-enact the Crucifixion, with the S-3 playing the starring role.

Eventually, with the deployment of the SURTASS ships, the use of the SQR-18A ships for tracking Soviet SSBNs was discontinued.

BangBangBangBangBangBang

One of the main tools of sailors (other than maybe the Radio-Girls) was a chipping hammer. It wasn't anything like a hammer, it was a flat bar of steel with one end bent over at a 90-degree angle. Both ends were slightly spread out as the steel had been flattened down so that the ends terminated in an edge that was sharpened at about the sharpening angle of a chisel.

What you did was to bang it against the deck or the hull in order to remove old layers of paint and, of course, rust.

It was really more akin to a scraper than a hammer. If you were to buy a chipping hammer from a store, it would have a handle with a spring-wire grip to lessen the shock of bashing it repeatedly against hard metal surfaces. The technique was to hold it loosely and to let the bent edge do the work.

If the work was heavy, then you'd use a needlegun. Needleguns were pneumatic tools. They were essentially rotating hammers. The hammer part was enclosed and it smacked a bundle of steel rods (the needles). You might even have a deck-grinder, which was a tool that had an abrasive drum. But those were expensive and if a sailor with a bad attitude chucked it over the side, they weren't replaced.

Once the old paint and loose corrosion had been knocked off, then it was time for priming and painting. Zinc chromate was used to prime aluminum (the superstructures of many post-war ships were aluminum) and red lead was used to prime steel. Red lead was reddish and probably had the lead removed long ago, but the name stuck. After the primer came the paint: Haze grey for vertical surfaces, a darker deck gray for decks, black non-skid for walking areas, and flat black for the upperworks above the top of the stacks. (Flat black went away after the steam ships were retired.)

It was almost a continuous process. The sea is a very corrosive environment. And there were damn few captains or chief bosun's mates who did not take pride in their ships.

Of course, the submariners loved to hear it. Chipping paint on a steel deck was like banging away at an underwater telegraph with the message "here be a Navy ship". Most merchant ships didn't have the crew to have a bunch of seamen out on deck, preserving and painting. So when their sonar watches heard the sound of steel being hammered, they had a good idea what they'd find.

The sonar gang on ships equipped with passive acoustic sonars hated chipping hammers for the same reason. The First Lieutenant and the ASW Officer were often close to being at war with each other. The First Lieutenant wanted his people keeping rust at bay, while the ASW Officer wanted the ship to be quiet to both reduce interference with the passive sonars and to reduce the chance of being detected.

That was a fight that the ASWO almost always won. Which didn't make the sonarmen popular with the deck apes when the deck apes had to spend a lot of their inport time engaging in Operation Sparkle.*

The compromise was that the deck apes got to use sandpaper and heavy steel wool, but no impact tools, to remove old paint and rust. Which was barely effective and often resulted in some painting over of rust that should have been removed.
_____________________________________
* One captain kept telling everyone that he wanted his ship to sparkle, hence the name bestowed on painting, preserving and cleaning by the crew.

The Last Frigate

The USS Kauffman is about to become the last of its breed.

When the ship leaves Naval Station Norfolk on Thursday for a six month deployment to the waters off Central America, it will mark the final deployment of a Navy frigate. The Kauffman will be part of a multinational, counter-narcotics operation known as Operation Martillo.

When the warship returns, it will be the last frigate in the Navy's inventory to be decommissioned later this fall.

Destroyer escorts/frigates have been serving the Navy for the last 74 years. The Navy has gotten rid of them, because DE/FFs were primarily ASW-oriented warships (the Battle off Samar notwithstanding).

To some extent, the Navy is replacing frigates with the Little Crappy Ships, because no other navy, at the current time, poses the sort of threat that the German and Japanese navies did during the war, or the Soviet Navy did during the Cold War. Other nations, however, don't seem to agree that frigate-sized warships are no longer useful. But those navies are looking at a larger naval power in their maritime neighborhoods, one with a submarine capability, and they may feel a need to prepare.

As maybe so should we. But navies are very expensive to build, train and maintain, and we're too busy chasing around tribesmen armed with rusty Kalashnikovs to worry about what may happen in the next decade or so.

The Return of DASH?

I wrote briefly about DASH (Drone Anti-Submarine Helicopter) in this post.

DASH was a failure for several reasons. It was too cheaply-made, with multiple sources of single-point failure which would result in the loss of the drone. Because of DASH's small size and the fact that no transponders were installed, they had a propensity to disappear from radar and once that happened, they were effectively lost. There was also no feedback from the drones to the ships; so the controllers had no idea what a drone might be doing at any given moment.

35 years after DASH was canceled, the Navy began trying again to operate drone helicopters rom ships, though not for ASW. But that'll probably come to pass in the not-so distant future.

Meep, Meep!

ASW, Japanese style:



(H/T)

ASW Weapons, the Conclusion

(Parts One, Two and Three)

The SQS-23 and other Korean-War era sonars, as I mentioned in Part 3, had the capability to detect and track submarines far outside the range of Hedgehog. The US Navy, among others, experimented with larger spigot mortars and rocket-thrown depth charges. Weapon Alpha was one that was largely unsuccessful.

All such weapons had the same problems; there was an unsatisfactory dwell time between the time the rocket was fired and the time the depth charge had sunk to the correct depth and detonated. All of those were predicated on the somewhat ludicrous idea that a submarine commander, knowing that he was being tracked by a destroyer, would hold a steady course and speed.

The answer was ASROC, for "antisubmarine rocket."

As you can see here, ASROC was a rocket which was fired from an eight-cell box launcher. The launcher itself used recycled deck mounts from 3"/50 guns. The rocket itself was a dumb, ballistic, solid-fueled rocket motor. Aiming was done by training the launcher and elevating the two-cell box with the ASROC to be fired. It worked out to be far more accurate than you might think.

On ships with Terrier (later, SM-1/2 ER) launchers (the DDG-37s, CG-16s and CG-26 class ships), ASROC was fired from the missile launcher. Each ASROC loaded was one less Terrier that could be carried. As the main mission of those ships was anti-air warfare, ASROC and ASW were the bastard stepchildren.

The business end of ASROC started out as a Mk.44 torpedo:


The Mk.44s proved to be unsatisfactory (among other things, it was slow) and were fairly rapidly replaced by the Mk.46. The torpedoes were active homers; they had a very high frequency sonar set. For guided weapons, they were the first true "fire and forget" weapons of the surface navy.

For close-in work, the torpedoes were also fired from deck-mounted launchers. Triple-mounts were added to a lot of ships:


The Knox class had twin mounts on either side of the after deckhouse, which were built into the deckhouse just forward of the LAMPS hangar.

ASROC also had a nuclear depth charge variant. This was the only live test, fired in 1962, before the Atmospheric Test Ban Treaty came into effect:

The nuclear ASROC worked like an old rocket-thrown depth charge, but with a hell of a bigger bang. The dumb-rocket version of ASROC left the fleet in the early 1990s when the ships with SM-1/2 ER or box launchers were all retired. A vertical-launch ASROC was eventually developed for use in current warships, though it reportedly was a pretty troubled development program.

ASROC could reach out several miles. But once again, the sensors outranged the weapons. The SQS-26 sonar, through either "bottom bounce" or "convergence zone" modes, could detect and track submarines way the hell out. The first solution was the Drone Anti-Submarine Helicopter, or DASH.

The concept of operation of DASH was simple: Fly the thing out until the markers from the sonar operator tracking the submarine and from the radar operator tracking the DASH converged, then drop the torpedo. Repeat if necessary (later models of DASH carried two torpedoes), then fly back to the ship for more fuel and torpedoes.

In practice, DASH didn't work so well. The drones were legendary for crashing and the DASH program was axed.

But that still left the problem that ships could track submarines further out than they could attack them. The answer was to provide ships with manned helicopters, the Kaman Seasprite, SH-2F LAMPS Mk 1:

LAMPS stood for "Light Airborne Multi-Purpose System," though a lot of sailors referred to it as "Lousy Air Mail and Passenger Service," for the best thing that the helo could for morale was to go get the mail from the carrier. The two drop-tanks you can see on this helo could be replaced by Mk. 44 or Mk. 46 torpedoes, though taking off a drop-tank reduced the in-flight endurance by 30 minutes. The red/white hashmarks outline the location of the sonobuoy launcher.

Late in the 1980s, LAMPS Mk.1 was replaced on the Spruance and Perry class warships by LAMPS Mk.3, which flew the SH-60F. The SH-60 program was supposedly the first aircraft procurement program where the prime contractor was not the airframe manufacturer (Sikorsky), but the electronics package manufacturer (IBM). Those ships were supposed to be able to hold two SH-60s. I never saw more than one LAMPS on a ship at a time and I think I maybe saw one SH-60s.

LAMPS would go out to the location of the submarine as determined by the active sonar track and stream a towed bird that contained a magnetic anomaly detector, the "MAD Bird." There were several different patterns the helo could fly to develop a track on a submarine; once the helo tracked it, it could drop a torpedo.

LAMPS also required a lot of people. The air detachment for LAMPS had three or four pilots and about 20+ sailors, with the senior officer being the head of the Air Department. More than one ensign or JG division officer in the other departments had more sailors and equipment to maintain than those four officers in LAMPS, which lead to the standard complaint of: "I know what they do to earn their flight pay, but what do they do to earn their base pay?" The corrosion control program for the helos required that they be frequently washed with fresh water (the fresh water usage of the LAMPS detachment routinely led to the Chief Engineer threatening violence upon the Air Boss).

LAMPS pilots were certifiable. Take a look at the photo of this Knox-class FF and note the size of the flight deck:

Now imagine trying to land a helicopter on that deck, at night, with the wind burbling around the superstructure and the ship rolling a bit. The LAMPS pilots did that, and the flight deck on a Garcia class FF was even smaller. They had to be nuttier than a jar of Planter's.

LAMPS became even more important when surface ships began to be fitted with towed array passive sonars (TACTASS, for Tactical Towed-Array Sonar System). If conditions were right, a towed array could be towed below the thermocline layer, down where submarines could hide from the hull-mounted sonars of ships. LAMPS were fitted with a launcher that fired off sonobuoys; little floats that dropped hydrophones deep into the water. The buoys had radio transmitters that send the signals to the LAMPS helo, which relayed them to the ship's sonar shack, where the signals were printed out on a frequency analyzer that was surplused from the P-3C upgrade program.

Sonobuoys came in several flavors. The ships had to pay for them and, as the ones with dumb omnidirectional hydrophones were the cheapest, those were the one used the most. There were sonobuoys with active pingers, but they were both costly and, as they alerted a sub that it was being hunted, not preferred.

Sonobuoys were used to localize a contact gained from the towed array. Once the contact was localized, the LAMPS helo would be vectored in for a MAD search. Once the helo had a MAD contact, then it was up to the three crewmen in the helo (two pilots and a sensor operator) to gain an attack solution and kill the submarine.

ASW Weapons; Part III

As I discussed in Part I and Part II, depth charges had several drawbacks. Chief among the drawbacks was the requirement that an escort prosecuting a submarine contact had to lose contact prior to launching her depth charges.

The Royal Navy had the lead on this problem, once again. They developed a "spigot mortar" that would launch a pattern of mortar bombs, each of which had a warhead of approximately 35lbs of high explosive. This became known as the Hedgehog. The mortar bombs were loaded onto rods; the bombs each had a cylindrical well along its center axis so that the bombs slid down and rested on the rods.


The early Hedgehog mounts were roll-compensated, but they could not be trained more than a few degrees to either side (moved from left to right) by tilting the mount, so the ship herself had to be aimed at the submarine. Later mounts were fully trainable. The mortar bombs themselves were launched in pairs at very short intervals, back to front, so that the bombs that fired at higher arcs were launched first (they had a longer flight time) and thus all of the mortar bombs would hit the water nearly simultaneously. The launchers' rods were set so that the bombs hit in a pattern, usually oval or circular, at a distance of 200 yards. The bombs would sink fairly rapidly.

Unlike depth charges, Hedgehog mortar bombs were contact weapons. Unless the submarine could hear the sound of the bombs being launched, she would not know that an attack run was underway, as escorts would also make non-firing runs to refine their targeting solutions. The time it took to reload the Hedgehog mount was usually less than it took to reposition for another firing run.

Hedgehog did have some of the same drawbacks as depth charges, in that the ships had quantities of high explosives on the weather decks. The launcher crews had to work topside, sometimes in far less than ideal conditions. At least one warship was lost when the stored Hedgehog bombs blew up because of faulty fuzing. They were also dumb weapons with a fairly long time between firing and impact, often close to half a minute or more, depending on the depth of the submarine.

Hedgehog nonetheless was a very lethal weapon when employed by a skilled crew. The USS England (DE-635) sank six Japanese submarines in 1944 in a period of 12 days.



Hedgehog was effective, but it still required that the escort close to the submarine's position in order to attack it. World War II sonars operated on sound frequencies around 14-30 KHz; many were "searchlight" sonars, such as the QGB sonar that transmitted a beam on one bearing; the sonar head was steered by the operator. The high frequency meant that the sonar head was small, it could be mounted on smallish ships, but because it was a searchlight system, searching for submarines was a matter of luck. The high frequency also limited the range.

Sonars developed into true search sonars that could transmit an omnidirectional beam. The QHB sonar transmitted an omnidirectional beam, but because it operated between 20 and 26 KHz, its range was limited. The early 1950s-vintage AN/SQS-23 sonar operated at 5 KHz, which greatly increased the detection range, but which also required a much larger sonar dome. The increased detection range of sonar sets like the SQS-23 meant that the escorts could track submarines far outside of the range of Hedgehog.

Clearly a longer range weapon was needed.

ASW Weapons; Part II

(Part 1)

To understand depth charges, you need to know that active sonar (the Brits called it ASDIC, for some obscure reason) did not exist in World War I. The British and American navies had been working on it for years, but it was not ready by Armistice Day. The ASW escorts charged the datum and began putting depth charges into the water. As submarines could not go very fast on batteries, if a destroyer got to the last known position fast enough, it was possible to catch the sub.

When active sonar was installed on ships between the world wars, the sets were at what now would be regarded as very high frequencies. That permitted small lightweight sonar domes, but also meant limited range. Those sonars were probably not good submarine detection sets; they had to know about where the submarine was.

There are four basic stages in ASW: Search, localize, track and attack. World War I destroyers were pretty deficient in the first and third stages, as they had no sensors, other than the Mk 1 eyeball, to detect submarines and no way to track them after they submerged. The early sonar sets were not much better on the search aspect, but once the crew knew where to look and got close enough, they could localize and track.

Depth charges had huge deficiencies. First off, they were horribly unsafe. They were often stored in racks on the weather decks, so each ship had thousands of pounds of high explosives just sitting on deck. They were vulnerable to shipboard fires, enemy fire and for getting loose in heavy seas.

Second, they were dangerous in use. If a depth charge that was rolled off the fantail detonated early, it could blow the stern off the ship. Even if it didn't do that, the shock could blow out the stern tube seals around the propeller shafts and sink the ship by flooding the engine rooms.

Third, blowing up a number of depth charges created a lot of regions of disturbed water, which obscured the sonar signals.

Fourth, sonars could not look straight down or to the rear. When the destroyer which was tracking the submarine commenced its depth charge run, it lost track of the submarine just before it got into position to launch the depth charges.

Imagine, if you will, that you are at a trap or skeet shooting range. You call "pull" and a clay bird is launched. You swing your shotgun towards the clay bird and just as the barrels start to swing into alignment, you close both eyes, try to maintain your swing and then fire.

Now imagine that the clay bird has the ability to alter its flight path and that the clay bird knows that just before you fire, you are going to be blind. The sub commanders knew that a depth charge run was underway and, as the destroyer came into position, the sub commanders would order a sharp turn. The destroyer commanders had to guess which way the sub might go and try to compensate. The sub might alter its speed, anything to mess up the depth charge run.

Something that was not known early in World War II was that the German boats could dive deeper than American or British submarines, in some cases, three times as deep. The Germans could go below the maximum setting of the early depth charges. Even when depth charges would detonate that far down, it took a bit of time for them to sink that far, which meant that actually hitting a deep sub was more a matter of sheer-assed luck.

Something had to be done.

ASW Weapons; Part I

At the turn of the 20th Century, a new development was coming into the naval scene: Steam turbines. Until then, the fastest screw-driven (ships are driven by screws, boat and airplanes use propellers) ships might approach 20 knots by the use of triple-expansion steam engines. Those engines used large pistons and crankshafts.

At the close of the 19th century, the Royal Navy unveiled a very fast boat named the Turbinia at the Fleet Review which was put on for Queen Victoria's diamond jubilee. Turbinia was the first successful craft driven by a steam turbine. Turbinia could reach nearly 35 knots, making her almost twice as fast as any other craft afloat.

During the era when the steam turbine was being developed, torpedoes were being developed. The first craft to carry torpedoes were light, fast boats. Somewhat larger ships, almost as fast, but more heavily armed, were developed to protect large capital ships from the threat of the torpedo boats; these ships were known as "torpedo boat destroyers." Torpedo boats would be used in wars through the Second World War. Torpedoes were also launched from larger surface ships, the Japanese "Long Lance" was the best in the world and was an extremely effective weapon. Torpedoes came into their most renown use as an antiship weapon launched from submarines, for they could be fired from periscope depth, giving the submarine the greatest possible concealment.

However, there was, at first no weapon specifically designed to fight a submarine. Gunfire was ineffective against a submerged submarine; shooting at the periscope was akin to trying to hit a broomstick at 500 yards with a rifle. And so, the first practical ASW weapon was developed: The depth charge.

The first depth charges were little more than cans filled with explosives. In a day when most buildings were heated with coal-fired furnaces, the furnaces had to be routinely cleaned of its ashes, which were put into large steel cans, or "ash cans." The depth charges were about the same size; they became known as "ash cans."
The early depth charges ones had 50lbs of explosive; by the end of World War I, they had up to 600lbs. The technique was simple: Go to where the submarine was and roll the charges off the stern of the ship. The depth charges had a delay timer, often set by depth, to prevent blowing the stern out of the water. If the skipper had an idea which way the submarine was heading, he could try to "lead" the submarine.

In order to get a wider pattern, the Y gun was developed. The Y gun threw two depth charges, one to either side of the ship.

The K gun threw one depth charge:


In the event that a submarine attacked the escort, the drill was to charge directly at the submarine at high speed (steam turbines, remember), which presented a narrow target for the sub to shoot at. If the sub was on the surface or had its periscope up, the bow guns of the destroyer would shoot at it to force the submarine below the surface. The subs of the day ran on diesels while on the surface and on batteries when submerged. The subs had to run slowly on batteries in order to conserve power, so if the destroyer could get to where the submarine was last seen (the "datum") very quickly, the destroyer would lay down a pattern of depth charges. If the submarine submerged too slowly the destroyer would ram it.

Depth charges killed in two ways. One was by concussion, which you have no doubt seen in any number of old war movies. But if the depth charge was close enough, the sub would be shattered. When an underwater charge detonates, it blows a circular bubble in the water as wide as water pressure will allow. The bubble then collapses to its center and bounces back out; this cycle repeats until it runs out of energy. But if as the bubble expands it touches a solid object, like a submarine, the bubble will collapse onto that object and blow the living shit out of it.

But there were serious drawbacks to the use of depth charges.

(To be continued)

Bet You Didn't Know This

On every warship with a SQS-26 or -53 sonar, there were sailors who had to be medically qualified to be divers. They weren't divers, they had no training as divers, but they had to be medically qualified as though they were divers.

In an earlier post, there were pictures of one of those large sonars. The sonar domes had rubber windows on them, for tests had shown that a rubber window was a lot better at conducting acoustical signals than a steel dome was. "Better" means that you might track a target that you couldn't or detect a target that you might have missed. "Better" means that you kill a submarine, and that, Gentle Reader, is what it was all about.

What you had, therefore, was part of a very large rubber tire on the front and sides of the sonar dome. A cruiser or destroyer could push that very large sonar dome through the water at over thirty knots. To prevent the rubber window from being pushed in from that much force, the sonar dome was pressurized with water. Fresh water was used in order to prevent the corrosion that would have occurred from sea water. There were high and low alarm points on the pressurization system, the alarms rang in both Sonar Control and on the Bridge. The importance of keeping the sonar dome pressurized was such that the alarm box was placed right next to the Captain's chair on the Bridge.

In really heavy seas, the bow of the ship would come out of the water, sonar dome and all. When the bow came back down, that large sonar dome would slam into the sea; the entire ship would quiver from the force of the impact and then the bow would continue down until the ship started up the front of the next wave. Warships did best in heavy seas by sailing into the waves. (By 'heavy seas," I mean seas with wave heights of thirty feet or higher.) If you were on the Bridge while that was going on, you would hear the loud beeping of the alarm as the dome was slammed down into the sea, as that would briefly overpressurize the sonar dome.

It was sort of an informal gauge of how bad the seas were by the number of beeps you heard from the dome alarm each time the bow came back into the sea. It was not unheard-of for a ship to suffer enough damage to its sonar dome in really heavy seas that the ship would have to be drydocked for repairs. (I'll blog about that process another day.)

Back to the point: There were periodic checks that had to be done to the interior of the sonar dome. If a bad sonar transducer element was detected during a source level check, it might need to be replaced. The sonar was designed so that you could replace elements of the transducer without having to drydock the ship. But keep in mind that you have a large dome that is, at its base, over twenty feet under water. That is a lot of pressure on the rubber window. What was done was that the fresh water in the dome was pumped out and replaced with compressed air. There was an air lock in the access trunk to the sonar dome. (A "trunk" on a ship is a narrow vertical shaft that goes through one or more decks.) The sailors who would do the work inside the sonar dome had to have diver's physicals, since they would have to work in a pressurized area.

And that is why you had sailors who had to be medically qualified for diving duty on warships.

Ping Time

Before I get to the story itself, first, you need some background information, so please bear with me.

Between the 1960s and the retirement of the steam tin cans in the 1990s, a number of them were equipped with the AN/SQS-26 sonar. The SQS-26 was a big sonar. If you compared a soft whisper to the sound of a very large jet airliner taking off and then used that scale to measure the sound of a SQS-26, the whisper would be the sound of the jet and the jet would be the sonar.

The sonar was so powerful that it could not be powered directly from the ship’s electrical system. A large motor spun a flywheel, which, in turn, spun a generator. That generator charged a bank of capacitors. These were not the kind of capacitors you could buy at Radio Shack, each capacitor was roughly the size of a quart juice can. If you shorted one out with your hand, your hand likely would be blown off. And there were a lot of capacitors in that bank. The whole lashup of motor, flywheel, generator and capacitors was the Louis-Allis Power Supply, known as Louie-Allis or LAPS.

This is the transducer array of a SQS-26:
A very large rubber radial belt goes around the front and sides to make up the dome's exterior. Each one of those black squares is the rubber face of a transducer element. You can roughly get an idea of the size of each element by comparing them to the worker in the background. There are hundreds of elements. When mounted on a ship, it looks like this:


This is the sound of one. That is what it sounded like if you were in a submarine and an SQS-26 was pinging on you from some distance away.

Every so often, the sonar techs had to measure the output and noise levels of the sonar, in order to do something or other. This was done in port; the sonar techs would hang a transducer from a pole so that it dangled in front of the sonar dome. And then they would ping away. This could only be done after normal working hours and with the permission of the naval station commander, for if a diver were in the water anywhere else in the the naval station when a SQS-26 pinged, the diver would be lucky if he only was rendered totally deaf for life. That level of sound could disorient a diver, who might then drown. Also, only one ship at a time could do the check to avoid mutual interference. You either got used to the sound of a sonar pinging at night or you didn’t get any sleep. And this check was done on just a few elements of the sonar for any one ping, by no means was the full power of the sonar used.

Now this is no shit:

A particular naval station had a bit where the ship at any given pier who had the senior-most commander was in charge of the security and good order of the pier. Those unlucky ships were known as the “Pier SOPA” (senior officer present afloat). It was a real pain in the ass to be the Pier SOPA.

One afternoon, the young lieutenant junior grade who was the Command Duty Officer of the ship that was the Pier SOPA looked out on the pier and saw that there was a really disorderly mess by one of the ships. That ship was across the pier from the Pier SOPA. It was a “United States Naval Ship,” which is an auxiliary ship (cargo, oil tanker) that is technically in the naval service, but which was commanded and crewed by civilian merchant mariners. USNS ships don’t do a lot of the mickey-mouse stuff that USN ships do.

The CDO had the Messenger of the Watch go over to the USNS ship and ask them to clean up their stuff on the pier and to tell them that if they didn’t, a working party would be sent to get rid of it. The CDO knew that the naval base duty officer would, sooner or later, make a tour of the piers and then the CDO would get chewed out for the slovenly condition of the pier.

Within five minutes, the Messenger was back with this message: “Lieutenant, the XO of that ship says that if we touch any of their shit on the pier, he will personally break your fuckin’ neck.”

As it turned out, the sonar techs of the Pier SOPA's ship had permission to ping that night. And it was after working hours. The CDO had the word passed for the duty sonar tech. When he showed up, the CDO ordered the sonar tech to light off Louis-Allis and get ready to start pinging on command.

The CDO went to Sonar Control and opened the door to the topside weather deck. By now, Sonar Control had a number of sailors in it, who had figured out that something good was about to happen. The CDO looked out the door and told the tech sitting at the console to switch to “track mode” and swing the track bearing to a relative bearing of 250 degrees.

Track mode concentrated all of the enormous power of the sonar into a beam of less than ten degrees in width. As you probably have guessed a relative bearing of 250 degrees aimed that beam at the USNS ship. The CDO ordered the sonar set for a short range scale (frequent pinging) and gave the order to start pinging.

WHAAANNGGGGG..........

WHAAANNNGGGG........

WHAAAAANNNNGGG.......

WHAAANNNGGGGGG.......

The effect on the USNS ship had to be akin to sticking one’s head inside of a large church bell while someone beat the living shit out of it with a heavy sledgehammer. The USNS ship looked as though someone had kicked over an anthill, as people came boiling up topside from below decks. In a few minutes, the Messenger of the Watch reported to the CDO that the XO of the USNS ship sent his respects and asked if the pinging could cease. The CDO told the Messenger that while the Pier SOPA had permission to ping, it could stop for a little while and oh, by the way, it’d be appreciated if they could clean up their shit on the pier.

The USNS ship had about 20 seamen on the pier in five minutes, squaring their stuff away. The Pier SOPA ship stopped pinging until the sonar techs were ready to do their checks. The naval station duty officer made his or her drive-by inspection and had no comments. And when the Pier SOPA had any future requests of that USNS ship, the USNS ship’s crew could not have been more accommodating.