The Sculpin’s Lost Mission: A Nuclear Submarine in the Vietnam War
By Admiral Charles R. Larson, U.S. Navy (Retired), with Captain Clinton Wright, U.S. Navy (Retired), and Paul Stillwell
One would expect that Cold War “special ops” involving U.S. nuclear-powered submarines are shrouded in secrecy. Other American sub-activities during that era, however, are also hidden, one for a very strange reason.
In 1971, after he had spent two and a half years of duty in the White House as naval aide to President Richard Nixon, Commander Chuck Larson was ready to go back to sea. He was ordered to be executive officer of the attack submarine Sculpin (SSN-590), under Commander Harry Mathis. For several months, the boat went through workups off the coast of southern California to prepare for a deployment to the western Pacific. That deployment included active participation in the Vietnam War.
After leaving the West Coast in January 1972, our first assignment was a classified special operation that lasted about two months. It went very well. The mission helped us hone our ship-handling and intelligence-gathering skills and made us confident in our capabilities and feel good about the way the ship was operating. Although it is still classified after all these years, it’s safe to say that it was intelligence-gathering targeted against the Soviet Union. Years later, Sherry Sontag and Christopher Drew’s book, Blind Man’s Bluff (New York: Public Affairs, 1998), described Cold War submarine operations. Because of security concerns, I can’t specifically discuss the contents, but the book is a good read.
After the special operation, the Sculpin went into Yokosuka, Japan, for some liberty, and my wife, Sally, met me there. I had grown my beard while at sea and that, combined with my black hair and pale complexion after the extended period underwater, made me look—according to Sally—like Rasputin, the mad tsarist Russian.
In March, shortly after we began our second operation, patrolling the South China Sea, we were diverted for a specific mission. The U.S. government believed supply trawlers were operating out of Hainan Island, off the southern coast of the People’s Republic of China. They were running arms, ammunition, and supplies from the northern part of the Gulf of Tonkin down to the Vietcong in the IV Corps region, the southernmost portion of Vietnam. U.S. forces discovered this when ground troops caught the enemy in the act of off-loading a trawler on a South Vietnamese beach. The incident sparked a big firefight, creating the legend that the trawler crews were elite forces willing to fight to the death. It also initiated a concerted effort to stop the traffic by convincing the enemy that it could not succeed.
Each of the trawlers could carry about 100 tons of munitions. Several suspect ships were photographed, so we knew generally what they looked like, but as long as they were in international waters, we had no means to interdict them other than to turn them around by making low passes with a P-3 Orion patrol plane or a close approach by a surface ship. This was complicated by the fact that so many legitimate trawlers like them were in the area. Several gunrunners had been turned around, but this would not stop the at-sea resupply effort. To convincingly discourage the effort, it would be necessary to destroy them in the waters off South Vietnam before they could land their cargo. The plan that evolved was to use a submarine to follow one from Hainan to South Vietnam and finger it for our forces to destroy. We were selected for this mission.
We took up a patrol station off Hainan on 10 April. After referring to a book with images of the different types of trawlers and what we could expect, we picked up our quarry on 12 April. The wardroom was divided on whether she was a good prospect. However, the ship resembled photographs of other known suspects, and her projected track was taking her toward the west coast of the Philippines, which did not make sense for a fisherman. So we took off in trail. Not long thereafter, the trawler turned to the south, and that was the clincher for us. She had an extremely distinctive shaft rub and propeller sound, which our sonarmen could easily discriminate from background noise. We relied completely on passive sonar to avoid being detected. The active sonar in the Skipjack -class submarines wouldn’t have been reliable because of the reverberations in shallow water.
The ship we followed was probably 200 feet long, a large trawler, certainly suitable for open-ocean fishing. We did, of course, identify her by periscope before we started to trail, but we weren’t able to follow her totally by periscope and maintain visual contact. We didn’t want to take the chance of having our periscope seen in the flat, calm waters of the South China Sea. Also, she was making a speed of advance through the water of about 11 knots. That meant that if we were going to do our periscope operations every now and then, get out radio messages, and do our required housekeeping evolutions, we were probably going to have to run an average of about 18 or 20 knots submerged to keep up with her. We also had to include time for ocean analysis and tactical maneuvering to make certain we were staying with the correct target.
One more challenge was that the trawler was heading south, right through the “dangerous ground.” On charts of the South China Sea, an area about 180 nautical miles wide and 300 miles long is simply labeled dangerous ground. Our charts had one track of soundings through that area—taken in 1885. We assessed that the terrain was fairly level, but the depth was 200 feet or less in most of this area. So we were in a position of running up to 20 knots in 200 feet of water, with between 30 to 80 feet under the keel at that high speed. Our ship could react very quickly to plane (control surface) movements, so we had only our most experienced officers of the deck, diving officers, and planes men on station. Our chief petty officer diving officers controlled the ship’s depth by supervising the planes men. They did a superb job.
As the trawler headed south, she vectored a little to the east and went into an area in the dangerous ground where we couldn’t go. Up to then, although we were in the dangerous area, we felt secure in knowing the bottom was fairly level. But now she went into an area that was littered with rocks, shoals, and shipwrecks. I wondered then if the trawler’s crew was smart enough to do what we called a “sanitization move”—go where even surface ships wouldn’t follow. She doubtlessly believed that if she went through there she would come out the other side well clear of any tailing vessel.
I was absolutely convinced that the trawler was unaware of our presence (that became clear later when we intercepted a radio message). We believed the ship’s course change was simply a safety move. While we were able to use our fathometer to plot the bottom and know the depth under our keel, the device looks only directly down; it doesn’t look ahead. We were genuinely worried about what we couldn’t see ahead—an undersea mountain, a wreck, or something else.
When the trawler had entered the dangerous ground, we requested cover from an on-call P-3 Orion. Although we were under the operational control of the U.S. Military Assistance Command, Vietnam (MACV) in Saigon, we had the ability to call the shots on the scene. We wanted the aircraft to remain covert, so it would not scare the trawler back into port by making low passes near her. During the ship’s voyage through this very shallow, wreck-strewn portion of the dangerous ground, the plane, remaining at high altitude to minimize the chance of being seen, kept track of her by radar and visual observation. We dodged around the area by hauling off to the west, then south, and finally back to the east, to an area where we predicted the trawler would emerge, still in the dangerous ground. As the P-3 turned the contact over to us, the trawler appeared just about where we thought she would. We picked her up from the distinctive shaft rub and propeller sound and got in close enough to get a good positive periscope observation. We then went back in trail.
As we headed south in the South China Sea, we approached a new hazard. We found a large number of oil-drilling platforms near the coast of Borneo. We first became aware of this hazard through the prolonged tracking of a diesel contact, which prompted the CO, Commander Harry Mathis, to go up to periscope depth for a look. We spotted an uncharted platform. If the rigs were operating, that was no problem; we could plot the location of their noisy diesel engines. We found some charted, some not, some operating and others not. Our concern, of course, was about those uncharted and not running. We made frequent periscope observations to avoid the platforms, which forced us to run faster to maintain the quarry’s speed of advance. We continued south at higher speeds for longer periods of time, sometimes with barely 20 to 30 feet of water beneath the Sculpin ‘s keel.
As our target passed between the Great Natuna Islands, we made an end run around North Natuna. After that, our quarry was on a beeline for the Gulf of Thailand, passing through the busy sea-lane between Hong Kong and Singapore. The density of the large shipping traffic in this lane was incredible. Crossing it was like running across a busy freeway. It was night time, and sonar was useless amid all the traffic noise, so we crossed at periscope depth following our quarry’s stern light, maneuvering to avoid the large ships bearing down on us from both directions.
The Gulf of Thailand presented a new challenge. The water was hot, 86 degrees Fahrenheit, and shallow averaging 110 feet deep, and the bottom was flat. The surface was a dead calm mirror with fishing buoys and nets everywhere, not to mention small fishing boats of every description. It was also very hazy and so hot that the horizon was somewhat obscure. Such were the wartime circumstances that our operation order authorized us to operate in water as shallow as six fathoms. Who says nuclear-powered submarines can’t operate in the littorals?
During this time we half-jokingly talked about “the hump.” We were trying to visualize what the Sculpin looked like on the surface, running at 20 knots, with maybe only 40 feet from the top of the sail to the surface. We visualized a hump—the water displaced above the boat’s hull—roaring through the South China Sea like a mini tidal wave, with observers wondering what it was. We assumed the ship left some sort of trail but were certain one would have to be very close to be able to see it.
An incident when I had command duty got my attention. I brought the Sculpin up to periscope depth and saw what I thought was a periscope going by. My first reaction was, “Holy smoke, there’s another submarine up here.” Then I realized it was a small water-saturated log that was floating vertically. Just for a moment I thought there were two submarines staring at each other and wondered which one was going to blink first.
As the trawler moved farther south, she made a distinct turn to the west and then to the northwest. We were absolutely sure she was a gunrunner, going into land and off-load her ammunition. Then, two things happened. We were ordered by MACV to photograph our target and alerted to prepare to execute a provision in our operation order for us to sink our target with torpedoes.
The photographic mission meant leaving our trail position and speeding up ahead of the target to take pictures as the trawler cruised by. The risk of detection was great because of the flat calm sea and our hump as we repositioned at high speed. To avoid this, we had to go as deep as possible. Commander Mathis selected 90 feet keel depth, leaving 20 feet between the keel and the bottom. We limited periscope exposure to 6 inches for less than ten seconds. We did get good pictures and apparently were not detected, although one photograph revealed three men on deck looking in our general direction. The depth control skill of our diving officer chiefs was extraordinary.
Immediately after the trawler made the northwest turn, and just before we communicated with higher authorities, we lost contact for about two hours. Up to that point, our target had been somewhat predictable, cruising on a straight course to the northwest near the center of the Gulf of Thailand about 100 miles off the coast of South Vietnam, with the familiar shaft rub being tracked by sonar. It was night with a full moon, and we saw her lights through the periscope. The horizon was indistinguishable. Suddenly, sonar reported she had stopped, and while the CO watched, the trawler turned off her lights. Blind and deaf, we then lit off the radar and made several sweeps that revealed nothing. This was not too surprising. When a radar hasn’t been used in months and is not tuned, taking it out and rotating it a couple of times doesn’t guarantee a high probability of picking up a small target. We were not sure whether she had stopped for the night or was moving away in a new direction at slow speed.
We reported the lost contact, which threw the operational command authority in Saigon into a panic. They had been moving South Vietnamese naval forces along the coast to maintain a blocking position based on our updates, so the whole operation threatened to unravel. Commander Mathis and I huddled and decided: “Well, we’ve got to assume that she’s making a run toward the border up there. Let’s just go down and run as fast as we can and get about 30 miles ahead of her predicted track and set up a barrier.”
So we moved up and waited for her farther up into the Gulf of Thailand. We made that sprint at 20 knots with 20 feet under the keel. At first daylight, we contacted our on station P-3 aircraft and described our quarry, particularly her white color. We requested the Orion’s crew search the area from where we lost contact to the Vietnamese coast. They reported several widely separated contacts; only one of them was white. The CO authorized a low-altitude identification pass, and the P-3 made a positive ID. They reported to Saigon, and we closed the target. As we neared, we regained that familiar shaft rub and when we took another periscope look, it was her—positive identification, both sonar and visual.
Originally, MACV requested authorization for us to sink the target with our torpedoes, but this was not approved. For years, I assumed that the National Command Authority in Washington, D.C., disapproved the request. However, several years later, Harry Mathis, who by then was a captain, was commanding officer of the Submarine Base Pearl Harbor. He regularly played tennis with retired Admiral Bernard “Chick” Clarey, who had been commander-in-chief Pacific Fleet at the time of our operation. Admiral Clarey remembered the operation very well because he and Admiral John McCain, commander-in-chief Pacific, had followed our progress closely in daily briefings. Admiral Clarey told Mathis that he had argued vehemently in favor of having us shoot, but Admiral McCain was not convinced it would work. Instead, South Vietnamese naval forces were called in to do the job on 24 April.
The surface forces—led by a South Vietnamese destroyer escort—challenged the trawler, which hoisted a Chinese flag and an international flag signal designating they were fishing. The South Vietnamese commander was hesitant to take action because he was concerned about creating an international incident. Fortunately, we established communications with the U.S. liaison officer on board the destroyer with the UQC underwater telephone. His first question was whether we could verify this ship as our trawler. We told him, “Absolutely, this is the one without a doubt.” We then went to periscope depth to observe.
The trawler tried to convince the South Vietnamese destroyer that she was an innocent fishing vessel. We spoke once again with the liaison officer and with higher authorities and said: “We are absolutely sure that this ship came out of Hainan flying a PRC [People’s Republic of China] flag. We have tracked her 2,500 miles to this position, and in our opinion, she is a gunrunner making a run toward the border and certainly is not a fisherman. We can verify who she is, which should allow us to take whatever action is appropriate.”
As we later learned from the intercepted communication, the trawler at one point said, “I think there is a submarine out there.” This was the first indication that the trawler crew was aware of us as we coordinated with the destroyer. Based on our identification, the destroyer escort ordered the trawler to stop, and when she failed to comply, began making intimidating runs at her, finally opening fire from a standoff position with her 3-inch guns. The trawler was hit and began burning, running in a circle as if the rudder was jammed hard over. We watched through the periscope, and our crew gathered in their mess to watch on the TV monitor. Suddenly, with a thunderous roar, clearly audible through the Sculpin ‘s hull, the trawler exploded and disintegrated as its cargo detonated. Flames leaped hundreds of feet in the air, accompanied by the cheers of our crew.
At this moment, Commander Mathis asked the crew over the 1MC for a moment of silence. Enemy or not, they had perished doing their mission. Later, we were pleased to learn that 16 of the trawler crew had been rescued and they spoke Vietnamese, not Chinese. The captain and the navigator were among them and able to provide valuable intelligence about their operations. One of the few casualties was the political officer.
Our communication with command headquarters, through the loitering Orion during the urgent final search, was vital. Only later did we learn that, because of atmospheric conditions, the communications link with Saigon consisted of the P-3 aircraft on station relaying to another P-3 revving up its engines on the ground at its airbase while parked next to a phone booth. A flight crew member would run out to the phone and relay the messages between Saigon and us.
One other significant factor made the mission possible. It could only have been done by a nuclear-powered submarine. That experience gave me great admiration for the diesel-boat crews and skippers of World War II. We had more margin for error than they did because of their speed limitations owing to low battery capacity. If we made a mistake on the Sculpin , we could make it up through speed and repositioning, which couldn’t be done with a diesel boat. Certainly our speed came in handy, not only in the basic trail, trying to stay up with a ship doing 11 knots and do all the things we had to do, but also during that period when we lost them. We were able to run quickly forward, reposition up the track, and get a chance to pick them up again. But that blackout period was a low point. We had trailed the ship 2,300 miles and thought we’d lost her.
The trawler’s crew verified that their ship was a gunrunner. They had on board enough arms and ammunition to supply the Vietcong in IV Corps for at least 60 days. Her destruction thus made a significant contribution to the safety of U.S. and South Vietnamese troops in the area and set back the enemy’s military operations there.
The surviving crew was North Vietnamese. They were split up, with U.S. and South Vietnamese intelligence each interrogating half and their stories compared. It was determined that the navigator’s responses were credible because he provided interrogators with exactly the same track we plotted.
The United States learned much about the North Vietnamese at-sea resupply strategy. It also learned that the trawler crews were not elite forces that would resist until death. One engineer told of being at his station when the political officer came to the engine room hatch, told him the enemy had arrived and ordered him to stay at his post. The engineer, no doubt considering the nature of the cargo, said, “I immediately went on deck and jumped into the water.”
It was an unusual operation. We spent more time submerged inside the 100-fathom curve than any U.S. submarine since World War II. Crew training, equipment reliability, ship control, navigation, sonar, communications, propulsion plant—everything and everyone performed superbly. We could not have asked for anything more. For that operation, the Sculpin earned the Vietnamese Cross of Gallantry, the only U.S. submarine during the entire Vietnam War to receive that award.
The Sculpin was also nominated for the submarine combat patrol pin, and our individual awards for the combat “V.” If that had been approved, she would have been the first submarine since World War II to get the combat patrol pin. Instead, the nomination was disapproved somewhere up the chain of command. I assume it was probably rejected by a World War II submariner who thought the operation wasn’t nearly as hazardous as what he did during his war, and it didn’t measure up. I can’t argue with that, but the crew had great hope that they could proudly wear the pin for their contribution, particularly to the safety of our troops. Another consideration, however, might have been that those pins would have raised questions and possibly compromised an operation that was still classified.
We covered a huge distance in trail during that operation. Someone asked me later how I slept at night. I said, “With a pillow under my head, up against the bulkhead in case we hit something.”
Admiral Larson went on to serve on active duty for 40 years. His senior position was as commander-in-chief of all United States military forces in the Pacific. Captain Wright served 26 years on active duty. He was commanding officer of USS Puffer (SSN-652) and operations officer for Commander Submarine Group Seven. Mr. Stillwell, the former editor of Naval History and the U.S. Naval Institute Oral History Program, has written the ” Looking Back ” column since 1993.