Incident analysis: Sinking of SLN Dvora craft

“The survivors have reported an underwater blast that damaged the boat's hull and caused it to be sunk in a short time. According to the survivors there has been no sea confrontation nor any LTTE craft were present in the area. Navy suspects the blast has caused by a possible sea mine or due to some underwater weapon developed by the terrorists.”
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by Commodore RS Vasan IN (Retd)

(March 28, Chennai, Sri Lanka Guardian) The sinking of a Sri Lankan Navy Fast Attack Craft P 438 on the night of 22nd March was reported. However, it appears that this incident has not been fully analysed or even if such an analysis was undertaken by the SLN the details have been withheld got obvious reasons. The Sri Lankan Government sources on 23rd March 2008 published a report with headlines ‘ Navy Fast Attack Craft sinks in mystery blast; 6 crewmembers survive ‘ The full report is given below: -

A Sri Lanka Navy Fast Attack Craft (FAC) has been caught in a possible underwater blast this morning (March 22). According to the defence sources, the locally built P438 deployed in northeastern coastal waters off Nayaru has sunk due the blast that occurred around 2.30.a.m.

Upon the receipt of the SOS message from the sinking craft other sea units have immediately launched a search and rescue mission in the area. According to the naval sources, 6 of the 16 crewmembers, including the Officer in Charge of the craft have been rescued so far.

The survivors have reported an underwater blast that damaged the boat's hull and caused it to be sunk in a short time. According to the survivors there has been no sea confrontation nor any LTTE craft were present in the area. Navy suspects the blast has caused by a possible sea mine or due to some underwater weapon developed by the terrorists.

Search and rescue mission continues.

The SL Navy’s report on its web, which had little, more details had this to say about the incident:

One locally built fast Attack craft out the two on routine patrol off Nayaru caught in an explosion in the wee hours today-the 22nd March, around 0200 hrs.

The boat being caught in the explosion started to take in water making it difficult for the crew to manoeuvre it to safe area. The impending consequence was unavoidable peril leaving the crew with no alternative other than abandoning the craft. Then they got onto life rafts and started drifting. Six members of the crew have thereafter been rescued by other boats. A search operation is still underway.

It is suspected that LTTE had unscrupulously laid sea mines in a bid of avenge due repeated losses in the recent past.

The report clearly suggests that there were no other boats in the vicinity nor was there a sea confrontation. The report indicated that the Navy suspected that either sea mines were used or “some underwater weapon’ developed by the terrorists. This analysis examines the possibilities of what could have caused the FAC to sink.

The Tamilnet quoting LTTE sources reported the sinking and credited three sea tigers including two women for the sinking of the attack craft. The names were given out, as Lt. Col. Anpumaran, Major Niranjani and Major Kaninila were the Black Sea Tigers killed in action. While the SLN said that there was no confrontation and the sinking took place due to a possible sea mine, the Tamil net claimed that the three black tigers engaged the attack craft. While the Tamil net said that fourteen crewmembers were dead, the SLN reported rescuing of six of the crewmembers.

Use of Sea mines. When the SL Navy made the announcement about the use of sea mines on its side of the IBL as a deterrent against the LTTE craft, it was obvious that if the SL Navy could use it, the LTTE could also resort to the use of mines in select areas. Knowing the technical and innovative ability of the LTTE the use of sea mines is hardly beyond their ability even if they have to improvise due to severing of the supply lines from the sea. As the readers are aware, the sinking of over a dozen sea going ships of the LTTE at extended ranges from the Sri Lankan shores has affected the capability of the LTTE. However, this has only forced the LTTE to find substitute material from the southern states of India.

Despite this limitation, it would not be a surprise, if some improvised floating sea mines were released by the LTTE in the expected patrol areas of the SLN craft based on intelligence and observation of movement of vessels. Depending on the depth in the area the possibility of using moored or ground mines in the area of operation of the SL Navy cannot also be ruled out. This incident of sinking of P 438 as it is reported to have taken place in deep waters indicating the ability of LTTE to strike in deep waters by using its underwater means be it mines or divers.

As per some reports on the official website The Sri Lankan Navy has not ruled out the possibility of a limpet mine being attached by the divers. However the fact that the Tamil net mentions about the engagement lasting 40 minutes prior to the sinking of the boat, precludes the use of limpet, mines. It is pointless to first attach a limpet mine and then engage the craft by black tigers.

Were underwater scooters/divers used? Some discussions are in order about “some underwater weapon” as reported to have been developed by the terrorists. What could this be is a question that would have many answers. One has to only go back to the reports carried some five years ago on 15th April 2003. The full report carried under the heading “LTTE use talks to obtain underwater scooters”


It was reported that the LTTE team had used its negotiating team in March 2003, during the CFA period to procure 34 underwater scooters from Denmark. The underwater scooters are mostly used by under water divers for sports and recreation. However, knowing the penchant of LTTE for innovation, they obviously decided that this could be used as a weapon. It is not known as to the fate of these 34 scooters and if the Sea Tigers used the same scooters. But if that could be procured then, one could procure the item under underwater sports category even today. A mere Internet search for underwater scooters revealed so many manufacturers from China to Australia to Norway. The range of underwater scooters allowed one to buy a scooter for as low as 800 dollars and up to 2000 dollars depending on one’s need.

Majority of the scooters are lightweight contraptions (15-20 kg), which could give an underwater speed of up to 1- 3 knots and could stay underwater at considerable depths for up to more than an hour. Using this device, a trained diver could easily remain underwater in the vicinity; carry enough explosives strapped on one’s person and carry out limited manoeuvre to detonate next to the patrol vessel with out being spotted. After all the LTTE is not new to loading boats, trawlers and humans with explosives for suicide attack. Essentially, this concept is nothing new as the concept of human torpedoes is as old as torpedoes themselves. The essential difference is that the scooters are much smaller than the chariots used by two divers for clandestine operations and enhance the staying capability of a frogman. There has been recorded use of divers on chariots for under water warfare by Italians, Germans, British and the Japanese during World War II. While some of them, which carried two frogmen, were designed to attach limpet mines to the underwater hull portion or propellers, the Japanese did contemplate the use of suicide divers.

It may be recalled that two frogmen were caught off Colombo on 17th Jun 2006 in an unsuccessful attempt to attach explosives on ships in the harbour. The divers who were caught did not succeed in swallowing the cyanide pills to commit suicide.

In conclusion, since the LTTE has acknowledged the loss of three of its cadres, the use of underwater scooters/chariots and explosive strapped black tigers this modus operandi appears to be the most probable cause of sinking of the patrol craft. The LTTE/fishing boats could also have been used to lure the patrol boat towards them thus bringing the craft in the harms way. While the type of threat itself is nothing new, if it is clearly established that a human torpedo or a sea mine of what ever description was used against one of the patrol craft successfully, then it does change the aspects of sea control by the SL Navy in its areas of operations. The Sri Lankan Navy which has enjoyed recent successes in its sea encounters has every reason to be worried about the type of the renewed under water threat that it faces now. It would now need to reevaluate its operational tactics adopt new methods to counter the threats posed by the Sea tigers.

(The author with distinguished naval and coast guard service for over 34 years is presently with Observer Research Foundation and is steering the Maritime Security Programme under the aegis of International Security Studies (ISS), headed by General VP Malik former Army Chief)
- Sri Lanka Guardian