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Offical History of Clearance Diving Team 3 Vietnam


Underwater attacks by enemy saboteurs were a serious threat to the merchant ships unloading at South Vietnamese ports. US and Vietnamese river craft, bridges and wharves were also subject to attack.


Swimmer sappers


The saboteurs, known as swimmer/sappers, were both specialist NVA divers, and Viet Cong who were given nine months training in North Vietnam. At the end of this course, they were capable of assembling and positioning land mines, command-detonated mines, and water mines, the last named being acoustic, magnetic or pressure-detonated.


Equipped with a snorkel, a limpet mine, grenades, a signal flare and a nylon line, the swimmer/sapper was able to stay in the water for some hours using currents and floating debris to assist his approach to the target. The major limitations on the swimmers were low water temperatures, strong currents, rough seas and the difficulty of underwater navigation at night.


Mines were often taken to the target area by sampan, slung under the vessel’s keel, if there was sufficient boat traffic to disguise the ‘minelayer’.


Harbour defence


The responsibility for the protection of shipping in the principal anchorages of South Vietnam against underwater attack was assumed by Inshore Undersea Warfare Group 1, Western Pacific Detachment, of the US Pacific Fleet.


Units of the detachment functioned in Vietnam as Task Group 115.9, the Harbour Defence Group, which was a section of Task Force 115, the Coastal Surveillance Force responsible for Operation Market Time. Like its parent task force, the Flarbour Defence Group had its headquarters at Cam Ranh Bay, southern Khanh Hoa province.


The harbour defence units of Task Group 115.9 carried out Operation Stabledoor, the defence of shipping against underwater attack in the ports of Cam Ranh Bay, Qui Nhon, Da Nang, Cua Viet, Nha Trang, Vung Tau and Saigon.


Each harbour defence unit was composed of three sections:


(1)    the harbour entrance control post, a command and communication centre which directed the movement of ships in and out of the ports and maintained communication with the craft of the harbour patrol;


(2)    the harbour patrol element which was equipped with various types of armed patrol craft and


(3)    the explosive ordnance disposal (EOD) team.


Clearance Diving Team 3


In 1966, there were two RAN clearance diving teams, both based in Sydney. One of these, Clearance Diving Team 1, had spent a short time in Vietnam in May of that year.


In early 1967, a third team of one officer and five sailors known as Clearance Diving Team 3 (CDT3), was formed for service in Vietnam. The tour of duty was initially six and a half months, but lengthened to eight and a half months for the last two contingents.


Assigned to the Vung Tau harbour defence unit, CDT3 had three main tasks. Its primary responsibility from February 1967 to August 1970 was Operation Stabledoor in the Vung Tau anchorage.


A second task was the disposal of faulty and expired ordnance in the Vung Tau area, a role which later expanded as the team was called on to dispose of ordnance in Phuoc Tuy province. To assist them in this task, CDT3 members were kept informed of new types of ammunition and the disposal problems associated with them by frequent orientation courses conducted by the US Navy in Saigon.


Finally, CDT3 was required to assist in salvage operations in the Coastal Zone 3 when the handling of ordnance was part of the salvage process. This particularly applied to crashed aircraft and sunken Market Time patrol craft.


Special Operations


An extension of CDT3’s EOD role which became important from mid-July 1968 onwards was special operations in which the team accompanied Vietnamese units and their US Navy advisers into Viet Cong-occupied areas using its demolition skills to clear canals of log barriers, and destroy tunnels and bunkers. Reconnaisance patrols and ambushes were also carried out in enemy areas. These operations involved CDT3 members in penetration of the Rung Sat special zone and the coastal areas of


Binh Tuy, Phuoc Tuy, Go Gong, Kien Hoa, Vinh Binh, Ba Xuyen and Bac Lieu provinces.




Led by Lieutenant M. T. E. Shotter, the First Contingent arrived in Vietnam on February 6, 1967, the first RAN combat unit to be sent to the Vietnam war.


The Australian divers were introduced to EOD under Vietnam conditions by being initially attached to a US Navy EOD team in Saigon which was split into two - each half of the US Navy team taking three CDT3 members on a separate operation.


At Thu Due, a village about fourteen miles from Saigon, one of the combined teams spent three days demolishing the remains of a bridge partially destroyed by the Viet Cong. A new bridge could not be built until the wreckage of the old one, both above and below water, had been demolished. The other combined team went to the US Navy river base at Nha Be, twelve miles downstream from Saigon and carried out underwater repairs on the minesweeper MSB 49. The vessel was successfully salvaged, and this work received the commendation of COMNAVFORV, Rear Admiral N. G. Ward USN.


Vung Tau


Twelve days after its arrival in Vietnam, CDT3 moved to Vung Tau and assumed responsibility for Operation Stabledoor.


Vung Tau, an autonomous municipality outside Phuoc Tuy province is situated at the end of a peninsula jutting into the South China Sea forty-five miles south-east of Saigon, South Vietnam’s capital and major port. Cap St. Jacques is the southernmost tip of the peninsula.


To the east, on the South China Sea, high dunes rise behind a wide sandy beach, while to the west the peninsula is dominated by three peaks of about 700 feet. On the seaward slopes of the centre peak (known as ‘VC Hill’), the team members made their living quarters in a disused ammunition bunker, part of an old French-built coastal fort in the harbour entrance control post compound. The inner shore of the peninsula, on the Baie De Ganh Rai is fringed with mangrove swamps and extensive tidal mud flats.


Nestling between two of the peaks is the commercial centre of Vung Tau and the fishing fleet harbour. The municipality extended as scattered villages along the inner side of the peninsula to the subport area and further on to the Cat Lo naval base. It encompassed a large military airfield from which US Army aircraft and No. 9 Squadron RAAF operated, while the 1st Australian Logistic Support Group was established on the dunes southeast of the airfield. A small subport was developed on the inner side of the peninsula. Its De Long pier was capable of accommodating ocean-going cargo vessels. In the Baie de Ganh Rai, four miles across the water from the subport, is the island of Long Son which was a base for Viet Cong incursions into Phuoc Tuy province, Vung Tau and the Rung Sat area.


The Cat Lo naval base was a US Navy logistic support facility and one of the major repair depots for patrol craft in southern Vietnam. It was also the headquarters of the Market Time patrol area, Coastal Zone 3 and the Vietnamese Navy Coastal Groups 32 and 33.


Vung Tau had two anchorages where merchant ships waited before proceeding to Saigon via the Long Tau channel through the Rung Sat mangrove swamps. Ships lying in these anchorages were inviting targets for swimmer/sapper attack.


Operation Stabledoor


Inspection of anchor cables, rudders and propellers, was carried out daily as a routine antisabotage measure, while hull searches were conducted on request, or following a report of a suspected swimmer in an anchorage. A tidal range of ten feet and currents of four to six knots in the Vung Tau anchorages hindered Stabledoor diving and anti-sabotage inspections. Fortunately, the same tidal conditions also made underwater navigation difficult for the enemy swimmer/sapper.


A typical Stabledoor patrol involved the team members driving the six miles from their quarters to the De Long pier and boarding the patrol boat which took them direct from ship to ship in the inner and outer anchorages. As they approached each brightly-lit ship, its sentry was hailed by megaphone, informed of the divers’ presence, and warned not to throw anti-personnel grenades into the water. (These precautions were necessary as it had been known for ship sentries to fire on harbour defence divers, mistaking them for enemy swimmers). The duty divers, with the officer-in-charge and a petty officer, then left the patrol craft for a rubber dinghy to approach the ship which was to be searched. The divers jumped into the sea and after examining the ship’s anchor chain moved along the hull followed by the dinghy. On completion of a search, the dinghy returned the divers to the patrol craft, which moved on to the next ship with the dinghy in tow.


Dawn Landing


CDT3’s first operation with VNN Coastal Group 33 was a dawn landing near Baria, Phuoc Tuy, on March 18. During the night of the 17th, a force of junks carrying Vietnamese soldiers arrived off a beach suspected of being used as an armament supply route by the Viet Cong. At first light, the accompanying VNN gunboat and US Navy patrol boat shelled the beach. While the soldiers secured a perimeter, the CDT3 divers checked ammunition boxes on the beach for boobytraps. None were found but a small quantity of American ammunition was recovered. Two Viet Cong river mines were destroyed after a round of sniper fire had drawn attention to their position, and the force returned to Vung Tau.


On March 28, the team examined their first Australian ship when the hull of MV Jeparit, anchored in Vung Tau, was searched.


EOD calls


Calls for the team’s assistance in disposing of dangerous ordnance became frequent by early April, so that by its third month in Vietnam, CDT3 was fully occupied in its EOD role.


The clearing of misfired ammunition was a common task for the team. One such instance was the removal of an 81 mm round from a mortar barrel on the light cargo ship USS Mark (AKL 12). The round had been in position for twelve hours but was successfully taken out after two hours of careful work. A week later, an old and dangerous 2-inch mortar round was removed from the 1st Australian Logistic Support Group area, Vung Tau.


Floating Mines


CDT3 was frequently called out to investigate objects thought to be floating mines. On inspection, the ‘mines’ were usually found to be wooden boxes containing ships' rubbish, used metal ammunition boxes, minesweeping floats, large mooring buoys, clusters of fishing stakes or empty garbage cans, and in November 1967 even a floating jar of the evil-smelling Nuoc Mam fish sauce was suspect. These mine scares usually led to a full scale air and sea search of the Vung Tau anchorages which required the attention of the team for several days. Junks acting suspiciously in Vung Tau harbour were also searched.


Helicopter salvage


On May 20, three team members were flown to Phu Loi, twenty-five miles north east of Saigon to assist in the recovery of a helicopter which had crashed in ten feet of water. Protected in the insecure area by two battalions of infantry, the team recovered two bodies, salvaged expensive equipment and finally rigged strops to the wreckage so that a Chinook helicopter could lift it back to Phu Loi.


Ship searches decreased rapidly in number near the end of May as the deteriorating weather of the advancing wet season made diving difficult. The weather also made it unlikely that enemy swimmers could operate in the Vung Tau anchorage.


In June, team members took part in a combined Vietnamese regional force and junk force landing on a small island in the Rung Sat. In the two-day operation, the CDT3 divers helped search three villages for ammunition caches.


In late July, three divers accompanied a reconnaissance patrol to the village of Xa Long Hai about fifteen miles along the coast from Vung Tau, to search for booby traps in villas that had once belonged to Madame Nhu, (sister-in-law of President Ngo Dinh Diem), and to South Vietnamese generals. After a period of Viet Cong occupancy, the villas were to be used by Vietnamese special forces.


Early in August, CDT3 and US Navy personnel assisted Vietnamese National Police by patrolling ‘VC Hill’ during the visit of President Ky to Vung Tau. Before the first contingent left Vietnam, a collection of ordnance and booby-traps had been assembled, and using this the team gave lectures to newly-arrived US Navy patrol boat crews on booby-traps likely to be encountered. They also instructed them in the techniques of searching junks. Occasionally team members would booby-trap a patrol boat after a lecture and its crew would be invited to test their newly acquired knowledge of EOD.


US Navy Commendation


For their service in Vietnam from February 19 to June 30, 1967, the First Contingent was awarded the US Navy Meritorious Unit Commendation. The Ambassador of the United States, Mr. W. Rice, presented the citation and commendation ribbons to 1st contingent personnel at HMAS Penguin in Sydney on September 23, 1969.