Prepare to Sweep Mines...

By Commander Murland W. Searight, U.S. Navy
Published in United States Naval Institute Proceedings, January 1970
Reprinted from Proceedings with permission: Copyright (c) 1970 U.S. Naval Institute

Not since they had been built, following the experiences of the Korean War, had Agile class ocean-going minesweepers been sent into a known minefield for a sweep under other than controlled, laboratory conditions. That is, not until 31 January 1968, when Mine Division 91 was sent into the Gulf of Tonkin to clear two known fields.


Toward the end of January 1968, MineDiv 91 was completing a 10-day upkeep period at Subic Bay in preparation for its third and last Market Time patrol of the current deployment. The upkeep had gone exceptionally well this time and the Division Commodore called the skippers into conference on the 25th. After consultation and ensuring that all loose ends could be picked up in time, he decided to sortie the division that evening rather than the following morning so that we could relieve MineDiv 71 a day early, allowing them to get a head start against the heavy seas on their long trip north to Hong Kong for rest and recreation. I led the way out with the USS Conflict (MSO-426) followed by the USS Endurance (MSO-435), and the USS Implicit (MSO-455). The USS Persistent (MSO-491), with ComMineDiv 91 embarked, brought up the rear. Once we had cleared the shelter of the harbor, we moved into stormy darkness and found ourselves rolling wildly in the trough, as usual.

We were assigned to relieve a station south of the Mekong Delta where our round-bottomed wooden ships would enjoy a much better ride than in the high seas of our previous patrols in northern waters. While still within radar range of Luzon, the directive was received to proceed independently as previously ordered, and we split up to go our several ways.

Two afternoons later, we were overtaken by the USS Aludra (AF-55). Thanks to an improvement in the weather, we were able to come alongside and receive fresh fruit, vegetables, and one vastly relieved storekeeper, who had reported in from leave at Subic Bay only to find all the minesweepers gone. We broke away and resumed course for Con Son Island, while the Aludra added a few turns and gradually pulled away.

She was not yet over the horizon when an excited messenger brought a message to the bridge hot off the wireless, directing MineDiv 91 to proceed immediately at best speed to Da Nang, to off-load magnetic materials, and to prepare for special operations. This meant just one thing; we were going to sweep mines, and it was no exercise! Speculation swept through the wardroom and mess decks as to the nature of our mission, particularly in view of the seizure of the Pueblo the previous week. The picture gradually began to come into focus as we picked off amplifying messages from the radio teletypewriter.

Around the middle of January, several mines had been accidentally lost in the operating area off the coast of North Vietnam, and there was reason to believe that the mines might be armed. In addition to the danger to our warships, the mines presented a remote but possible hazard to any other ships that might stray from the regular shipping lanes. Hence, the nearest division of minesweepers was ordered to sweep these fields, thus becoming the first of their class to perform their primary mission under a fully operational wartime situation.

MineDiv 91 had several factors working in its favor, not the least of which was an unusually experienced and knowledgeable commodore, Commander Russell Bridgham. All the ships in the division, under their present captains, had completed mine countermeasures refreshing training just before deployment, and the entire division had successfully met their magnetic signature requirements only a few days before while in Subic Bay. Notwithstanding the material and logistics problems engendered by sustained independent Market Time patrols, our minesweeping equipment was fully operational.

The remainder of the transit to Da Nang was occupied with preparations for the imminent operation. Sonar, radar, degaussing, and minesweeping control circuits were checked and peaked to top performance. Procedures were reviewed, and drills were held in the myriad and peculiar aspects of taking our small ships into such dangerous waters. Bridge awnings were removed and the overheads of radio central, combat information center, and the pilothouse were padded to protect the skeleton crews against underwater explosions. All other men would live above decks for the entire period of the operation. Even the engineering spaces would be deserted, with all control being exercised remotely from the pilothouse. Magnetic, acoustic, and moored minesweeping gear was streamed and double-checked. I prepared a mine hunting plan designed to minimize mutual sonar interference and maximize the likelihood of early discovery of mines. We would be using the latest, high resolution mine hunting sonar, new with our divisions.

The Conflict was the first to anchor at Da Nang, the morning of 29 January. I took the motor whaleboat ashore and made arrangements to refuel the division, as well as arranging for the off-loading and safe storage of all magnetic material from the four ships. Late in the afternoon, I took the ship into Hai Quan pier. This was an evolution I normally rotated among the officers, but I wanted this landing myself for two reasons. The basin was tightly restricted in maneuvering room, with a fresh breeze setting toward the pier allowing very little room for errors and very little time for me to monitor and correct another conning officer. Besides, I was nearing the end of my command tour, and I hugely enjoyed handling these highly maneuverable vessels, with their twin rudders and variable pitch screws.

Once alongside, all hands turned to the task of offloading all magnetic materials except those essential to the forthcoming operations. Even such things as wire coathangers, swords, and cans of shaving cream had to go. Those ferrous materials needed on board were carefully positioned and oriented in accordance with our magnetic materials control bill. The sophisticated degaussing system compensated for these items, reducing our already naturally low magnetic signature to almost nothing. This elaborate procedure, of course, is to reduce the hazard to the ship when operating over magnetic mines. In addition, a quiet ship bill is implemented to make the ship less vulnerable to acoustic mines, with much of the auxiliary machinery stopped or operated at reduced speed. Finally, the ship’s slow speed and light displacement provide protection against pressure mines, and careful mine hunting ahead of the ship by sonar makes it possible to avoid moored contact mines. On the other hand, modern mines are very sophisticated, and it is not practically possible to completely ensure the safety of ships that pass them close aboard.

We were able to complete our off-load and inspection in about two hours, and return to the anchorage shortly before the Persistent, the division flagship, arrived in port. Late at night, when the last of the ships had anchored, the captains assembled in the commodore’s cabin for his briefing and co-ordination of tasks. Minesweeping equipment was consolidated in accordance with individual assignments, and my mine hunting plan was accepted. We then returned to our ships and double-checked our security measures–the gunfire of the enemy Tet offensive was clearly evident around the harbor– and finally turned in.

Tuesday the 30th saw the other three ships refueled, and each in her turn went alongside the pier and stuck magnetic material into large crates, which would be locked and stored by the local Naval Supply Activity. By mid-afternoon, we weighed anchor and steamed in column formation out of the harbor, then turned north. After dark, there was a final division drill at general quarters, and with all exterior lights extinguished, the darkened ships pressed on into the black night along the hostile enemy shores.

After breakfast the following morning, we arrived at the first of the fields and stationed the mine hunting detail. Conforming to standard procedures, the motor whaleboat was lowered to the rail and griped to the side, an impressive reminder that its immediate use might be required.

When all ships were ready, we began a preliminary search of the bottom. The floor of the Gulf proved to be littered with objects the size and shape of mines, and after a couple of hours the Commodore abandoned the fruitless task of trying to identify each of them, and elected to begin sweeping operations while continuing hunting procedures. Just before we prepared to set up for sweeping, a message arrived giving a corrected position for the field. We fell into formation and sailed toward the new datum a few miles away. We were joined by the USS Dale (DLG-19), assigned to provide protection for the vulnerable minesweepers. Her presence was most welcome, for the heaviest armament in our division consisted of a temporarily mounted twin 20-mm cannon on each ship–not much protection for anything more threatening than a junk.

Upon arrival at the new datum, the Conflict was detached and directed to plant a master reference buoy, establishing a marker for minefield navigation. This exacting and vital evolution was completed with some greatly appreciated positional assistance from the Dale, and after assuring ourselves that the buoy was “watching” properly, with its radar reflector and high visibility flasher operating, we made one mine hunting pass around datum without result, then hauled out to stream gear.

Even under favorable conditions, this is a hazardous and exacting challenge of seamanship to any mariner. Equipment must be winched over the side and placed in the water near the screws and rudder while maneuvering in formation. Kites, pendants, and floats are rigged to provide the proper operating depth and diversion from the sweepers path. If the sweep is for moored mines, explosive cutters are installed on the sweep wire and armed. If acoustic devices or magnetic tails are used, they must be tested and powered. In the case of magnetic sweeps, this may be several thousand amperes, adding to the danger of handling running rigging that is under strain. Once the equipment is streamed and riding properly, the conning officer is required to thread through complex sweep paths with the nicest navigation and station keeping to prevent “holidays”–blank areas–in the sweep paths, while his maneuvering options are markedly restricted. If he turns too sharply, the gear on the inside of the turn may sink, or the cable may bottom and part, while the outboard gear shears wildly because of increased speed, perhaps porpoising or even parting under the additional strain. Even on a steady course, speed changes are restricted to a rather narrow range for the same reasons. With so little leeway for corrections, the conning officer must be very nearly in the right position, all the time. Added to the difficulties in this case, we were now streaming gear in enemy waters, on a pitch black night in a cold drizzle, with the knowledge that somewhere, down there, were mines.

Shortly after midnight, all four ships had their gear streamed and tested and were carefully maneuvering into an echelon formation for their first pass through the field, with the Persistent in the lead, and the Conflict in third place. At this most critical of moments a cry came from the boat deck:
“Captain, the boat falls have parted. The boat’s in the water!” However humorous such events always seem in retrospect, they certainly tax one’s composure at the time. There we were in formation, with hundreds of yards of minesweeping gear hung from the transom, sandwiched between two sister ships with their gear similarly streamed, on the verge of entering a minefield. The wind and seas were on our port hand, and the boat, now hanging by her forward falls was buffeting the port side. Boat hooks, life buoys and jackets were floating away, lanterns and heavier gear were gurgling to the bottom. I got off a quick voice signal to the commodore and maneuvered as best I could to satisfy the contradictory requirements of the emergency: maintain enough speed to keep the gear from riding up astern and maintain steerageway, but slow down enough to reduce the banging of the boat; haul out to starboard to clear the minefield, but don't get in the way of the Implicit which was following on our starboard quarter; change course gradually to protect the gear, but come about as sharply as possible to provide a lee on the port side, while taking care not to fall into the trough of the seas at low speed with gear streamed.

I slowed from six to four knots, coming left as hard as I dared while keeping an anxious eye on “Oscar,” the lighted float at the end of the gear, and signaled the Implicit to pass under my stern and come up my port side. As the bow came through the wind, the seas along my port side decreased substantially, and I decided to attempt the boat recovery without hauling in the gear. By this time, the executive officer had rushed from the combat information center and taken charge on the boat deck while the first lieutenant/mine countermeasures officer was occupied tending the gear aft. The forward falls were paid out until the boat was riding safely alongside, although awash to the gunwales. The cause of the casualty was found to be a spliced eye that had pulled open, and the boatswains mates quickly shackled the bitter end back in place and rethreaded the falls on the drum of the boat winch. A trial of the boat winch showed us that while we could hoist the water-filled boat at most a few inches to add freeboard for pumping her out, in that position, she was being badly buffeted against the side, so the falls were slackened. A submersible pump was lowered into the boat, but it obviously needed better tending than could be provided from the boat deck. The executive officer Lieutenant Joe Procopio, requested permission to enter the boat, and after a moment’s hesitation, I agreed. It was hazardous but necessary, and Joe was one of the most capable and resourceful seamen I knew. This sort of challenge was just his cup of tea.

Decked out in lifejacket, flashlight, and whistle, and tended by a line, Joe went over the side, splashed into the swamped boat and received the submersible pump. Progress was slow; for, as the pump lowered the water level in the boat, swells would wash over the gunwales and replace the lost water. Nonetheless, we eventually got enough freeboard so that he was able to get most of the water out of the forward well, then the engine compartment, and finally the after well. A strain was taken on the falls, Joe pulled the plugs so that the remaining water could drain as we hoisted the boat clear of the water, and he came back aboard.

The boat was about a foot off the water when the hoisting pad eye on the forward davit, weakened from the pounding it had taken, suddenly gave way. We were now worse off than before, with the boat being dragged by her painter, bow-down through the water. By this time we had been on a steady course long enough for the gear to be streamed well clear, so I was able to slow another knot. Without an attachment point, however, we could not now use the forward falls on the boat winch. The problem was attacked by attaching a nylon mooring line to the boat’s forward hoisting pad, reeving it through a highline block rigged in place of the davit wire block, and by using a couple of snatch blocks, fairleading it athwartships through a passageway to the minesweeping winch on the starboard side of the boat deck.

Once again Joe went over the side and resumed pumping operations. We suffered more of the “50 gallons out, 40 gallons sloshed back in” business while I went to the bridge to make another situation report to the incredulous commodore. After a pause, he gave me a weary “Roger.” He had his hands too full with three ships in the minefield to give too much concern to a problem which seemed to be under control again, sort of.

I turned to go back down to the boat deck, and my heart stopped. Joe was spread out in the stern compartment of the boat, with his arms and legs extended and his head lolling across the gunwale. “My God!” I thought “Joe’s dead,” as I raced for the ladder. After only one or two very long seconds, I was immensely relieved to see him raise his head, check the pump, and recline again for a little bit of much needed rest. When the water was once again down to about the deck plates and the pump started to lose suction, Joe pulled the plugs, flipped a wriggling fish from the stern compartment, and returned on board. He was later to claim that he had been attacked by that mad minnow. Once again we began hoisting, this time carefully co-ordinating the after falls on the boat winch with nylon the nylon mooring line on the minesweeping winch. Little by little, the boat came up until she was just clear of the water, but the load on the nylon line and its winch were just about as great as they could handle. We anxiously watched the stretched line while the last few inches of water drained out through the boat plugs, then ever so carefully, heaved around again until the boat was high enough for us to crank the davits in the grip the boat to the skids. It was a tremendous relief to finally set the boat onto her blocks and report her successful recovery to the commodore.

Although we no longer had a lifeboat available, and our damaged one was not stowed for a proper magnetic signature, I reported that the Conflict was otherwise ready to resume sweeping operations, and we took up last position in the echelon as soon as we were able to rejoin, three hours after the boat casualty.

The Persistent, Endurance, Implicit and Conflict passed up and down their lanes, gradually working towards the center of the field. The eyes on the bridge strained into the darkness, watching for the ship ahead with his “Oscar” winking not far from our bow. Lookouts aft monitored our own gear and all hands waited for the “WHUMPH!” which would come if and when we lifted a mine, hopefully with our gear rather than with the ship. Watches were port and starboard for most people, port and port for some. Lieutenant Procopio and I alternated on the bridge and in combat information center, eyes glued to the sonar display. Those men not on watch and not required to be in the padded spaces, huddled on the wet, cold deck in their foul weather clothing and slept when they could. When we completed each pass through the field and maneuvered to re-enter, the enginemen could make a quick pass through the engineering spaces, head calls could be made, and the cook could draw some hot coffee to ease the miserable conditions topside. Joe or I could close our eyes and rest for a few minutes.

MineDiv 91 swept for another 24 hours, finally recovering all gear just before dawn on 2 February. There was another field to be swept a few miles away, but the crew had their first chance in a day-and-a-half to go below decks, shower and shave, get some hot solid food, and get a short nap in their own bunks rather than on a wind and rainswept deck. At 1015, the entire sequence (except for the whaleboat casualty) began again and continued until 1919, when the commodore wired that both fields could now be considered swept clear. We had not actuated any mines in the rather accurately known positions of their loss, indicating that either they were properly on safe when they went into the water, or they had already exploded. This, of course, is something that mine countermeasures forces never know until the operation is completed. In any case, it was now safe for other forces to operate in these areas, and the ships of MineDiv 91 once again demonstrated the motto of the mine forces. “Where the Fleet goes, we have been.”

At 1915, the Dale departed and a weary, cold, and hungry mine division set course for Da Nang, anchoring there the evening of 4 February. The following day, the division refueled and reloaded magnetic material. The Conflict completed her onload and departed for southern waters at 1516 to relieve the Dynamic (MSO-432) ten days later than scheduled.

Valuable lessons were learned at all levels of authority from this experience. The Mine Force of the Pacific Fleet demonstrated dramatically a readiness and capability to conduct sustained minesweeping operation on short notice. At the same time, it was glaringly clear that other operation requirements had fully committed MSOs outside their primary areas of responsibility. Material problems that had long been deferred were abruptly spotlighted. Tactical and administrative procedures were tested under much more severe conditions than exercises provided. Perhaps best of all, attention was refocused, at least briefly, on an all-too-often neglected but vital component of our Fleet capabilities.




The USS Conflict (MSO-426), like the 56 other Agile-class minesweepers that were built between 1952 and 1955, displaces 750 tons; her wooden hull is 171 feet long; and she carries a complement of about 75.


A graduate of the University of Southern California, Commander Searight enlisted in the U.S. Navy in 1942 and rose to Chief Aviation Electronics Technician before being commissioned at OCS Newport in 1955. He served in the USS Hancock (CVA19) from 1955 to 1958; in the USS MacDonough (DLG-8) from 1961 to 1963; he commanded the USS Conflict (MSO-426) from 1965 through 1968, including two Market Time deployments. Since 1968, he has been assigned to the Center for Naval Analysis, Arlington, Virginia.