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From the RNA General Secretary: 


In the wake of the US assassination of Gen Soleimani, I thought RNA members might be interested in an article originally posted in June last year but which remains highly pertinent at the beginning of 2020 with the news of RN assets being sailed to protect shipping through the Straits of Hormuz. The article is reproduced in full with kind permission of the author, Mark Gray MBE


Gulf of Oman Attacks: what’s happening and what can be done about it?


All timings local.


In the early hours of 13 June 2019 explosions ripped into the hulls of the tankers MV Kokuka Courageous (KKC) and MV Front Altair (FTA), causing damage to both vessels and leading both to be evacuated and left drifting. There is a growing array of theories (including the usual conspiricists) but, for the moment at least, few facts. Having reviewed the open source information available (and only that) over the past 48 hours, the following possible sequence of events is offered.


Iran is clearly suffering from the effect of the re-imposed US sanctions and, for reasons that do not yet appear to have an obvious route (to me, at least) to achieving their desired end-state (relaxation) has decided to threaten the oil and gas supply chain from the Gulf, creating uncertainty in the global markets. There is historical precedent, although the success of that venture is unclear, but the Iranians certainly have leverage, and intend to use it. They are well versed in the tactics of the indirect approach. For the moment, we will leave “motive” there. If the intent is correct, the means strike me as counter-intuitive – but I am about as far from an Iran expert as you can get. Perhaps others may share a view.


MV Kokuka Courageous (KKC)




IMO: 9568495




Flag: Panama




Cargo: 25,000 tonnes’ methanol




Location at moonset: 25°53’N, 056°59’E




Location at detonation: 25°23’N, 057°40’E




Speed at detonation: 14.3 knots




Damage: small hole and scorch marks on starboard aft quarter;


object fitted to hull approx. 3ft above waterline on starboard for’ard




As to the events, the facts that are known are these: two laden tankers suffered explosions and damage in the Gulf of Oman, as they were steaming from the Gulf to the Far East. Nobody has claimed responsibility; fingers have been pointed, and there have been counter denials. The crew have reported seeing “flying objects”, the US Government has shown grainy and inconclusive footage of what they described (credibly) to be an Iranian warship removing a limpet mine from the side of KKC. There is no smoking gun as yet. From these facts, and some others, the following theory for the events of that morning are offered.


Both KKC and FTA passed through the Straits of Hormuz (SoH) shortly after midnight on 13 June. Both passed through the eastbound zone of separation (ZoS) and steamed south hand-railing the Iranian coast at a distance of approximately 12-15nm (12nm being the territorial limit of Iranian sovereignty, although legally nothing could stop them transiting through Iranian waters if they wished. A waxing gibbous (three-quarter) moon shone brightly in the sky at this time, but low in the sky and getting lower and increasingly dark.


MV Front Altair (FTA)




IMO: 9745902




Flag: Marshall Islands




Cargo: 75,000 tonnes’ naphtha




Location at moonset: 2610’N, 05647’E




Location at detonation: 2526’N, 05723’E




Speed at detonation: 10.9 knots




Damage: three separate visible fires on starboard side midships,


aft quarter and for’ard quarter


A couple of hours later, at 0226 hrs, the moon set. Shortly afterwards (but before first light at 0427 hrs), it is probable that a number, at least two, Iranian Revolutionary Guard Corps Navy (IRGCN) small craft edged across to the shipping lane, specifically to target these two vessels. The attack craft will have been small and low profile, to offer negligible radar signature, fast, to enable a quick getaway, and manned by sailors armed with compact limpet mines of between 5-10kg of high explosive. Once the moonlight had gone, allowing them near total darkness, the craft sneaked up the wake of the two vessels. A modern ship’s night watch normally comprises two persons, a navigating officer (who may be the Master, but normally not at night, unless that part of the passage is high risk) and a seaman lookout. These may be augmented when close to land, in busy shipping lanes or where there is another type of threat e.g. piracy. It is possible that an augmented watch was stood to for the SoH passage, but might have been stood down once clear of the ZoS. The role of the seaman lookout is exactly that – to look out. The principal concern is for things to the front: land, other ships, objects in the water (e.g. “lost” shipping containers) and pirates. For the most part, threats do not come from behind, and therefore the lookout rarely looks that way. Additionally, few bridges have windows that look to the rear, so in order to view to the rear, the lookout has to leave the comfort of the air-conditioned bridge, onto the external bridge wing where temperatures even at night can be quite uncomfortable. Mother nature and modern ship design actively discourage rearward facing lookouts.


The task for the IRGCN craft, therefore, is relatively risk free. Coming up the wake of the target affords them the greatest opportunity of reaching the target undetected. The target’s own engines and propellers would mask the sound, the watch’s eyes are looking forwards and it is pitch black. My own experience in the Royal Navy chasing pirates off Somalia, suggests that the radar signature of a small craft is negligible – from a warship’s powerful radar we could only see pirate skiffs on radar at around 500m and only in a flat calm sea. At almost any sort of sea state this range reduced to 200m or disappeared altogether as the wave height exceeded the height of the craft’s gunwales. Warship bridges are manned by an army (!) of people, each sensor being stared at by watchmen, both on the bridge, or deep in the ship’s operations compartments. The navigating watch officer on a modern ship’s bridge is monitoring a number of systems – 2-3 radars, AIS, GPS, electronic charting (ECDIS), VHF and probably also e-mail comms. On many ships these systems are combined into a single display, which aids monitoring, but would lead a small, weak radar return to disappear into the noise of all the other data. The officer might only consult the display every 5-10 minutes, just checking out what is ahead of him in the next 10-15 mins, while he chats to the lookout, or sends WhatsApp messages to his family. It is not likely that he would have been “staring” at the display non-stop for his whole 6 hour watch. My contention, therefore, is that the task of sneaking up undetected on the stern of a modern tanker steaming at 14 knots, on a moonless night is not much of a challenge.


For reasons I shall come on to, the devices planted by the IRGCN teams were planted on the beams of the target vessels. This required them to move forward of the bridge and significantly increases risk of detection. They will likely have remained as close to the hull as possible, and slid along the side of the ship for’ard to the planting positions. In doing so, they would have potentially exposed themselves to the possibility of being seen by the lookout. However with the lookout inside the bridge, possibly close to the centreline of the ship, his view of a small craft nosing up the starboard flank would likely have been masked by the ship herself. Were he placed more to the starboard side of the ship or on the starboard bridge wing, it might be possible for him to see down the flank of the ship as far as the waterline, had that been what he was looking for. Even so, the very bright deck lighting that tankers show, would cast a dark shadow in the exact space that the IRGCN craft would be exploiting. So I contend that even if he were in the best place (the starboard 25% of the bridge space, or on the bridge wing) to have a chance of spotting a craft sneaking along the ship’s starboard beam, the lighting configuration would likely have denied him the opportunity of doing so.


With those points being made, it is highly probable that a single, low profile, fast IRGCN craft could sneak up to a target vessel steaming at 14 knots and place limpet mines on the starboard side of the vessel and once complete drop back into the vessel’s wake and escape undetected.


There has been much speculation on the cause of the detonations on the two target vessels, with initial reports suggesting torpedoes and the Japanese owners of the KKC contradicting the US limpet mine theory by reporting crew members’ sightings of “flying objects” at around the time of the explosions. Torpedoes are out of the question as all damages appear to be above the waterline. It would be interesting to be able to quiz the crewmembers who sighted “flying objects” in detail, but without that opportunity and to support the limpet mine theory, I can only suggest that it is possible that the IRGCN were operating drones around the ship(s) at the time of the detonation in order to get immediate feedback on the success (or otherwise) of the tasks. Again, in darkness, the drones would have been able to stand off, undetected, but once the detonation occurred (after first light) moved closer to get better footage. It is possible that this is what crew-members saw.  


That leaves limpet mines. Relatively small metallic, magnetically affixed explosives containers. Limpet mines are very effective. Explosions naturally take the path of least resistance, so a detonation on the side of a vertical sheet of 10mm steel plate will mostly go outwards. Limpet mines work because underwater, the pressure of the water on the outside of the mine forces a far greater proportion of the blast into the hull of the ship and gives the additional “benefit” of creating a large hole for water to flood into. The IRGCN had few options, however. They could have affixed limpet mines to ships at anchor below the waterline off Fujairah, but they have done that a few weeks back and as a result the Fujairah anchorage is now well patrolled. They could have done so in the ships’ loading ports, on a timer, but affixing limpet mines to ships below the waterline is difficult – barnacles and weed on the ship’s hull reduce the efficacy of the magnets and once the ship is steaming at 14 knots, the drag induced by the poor streamlining would likely rip it off anyway. Besides, sneaking into anchorages in any of the major Gulf ports is a significant logistic challenge even for the IRGCN and would introduce a whole raft of additional risks, compromising deniability. So the attack team had no option but to target the vessels while steaming. This naturally precludes a below-the-waterline attack, since it would be impossible to affix onto the hull of a ship doing 14 knots – the drag on the operators hand caused by water moving past at 7.2 metres per second would deny success, and the device would likely be ripped off by the force, even if achievable.


Therefore, the plan will have been to place the devices on the clean hull above the waterline (no detritus to compromise the magnet) accepting the disadvantage that the effect of the detonation would be significantly reduced as the bulk of the force would press away from the hull, not towards it (more on this shortly). The other obvious disadvantage, of course, is detection. In broad daylight two or three new “appendages” on the side of a vessel would be very noticeable – probably not to the crew of the actual vessel themselves, as they would likely be out of their vision, unless they were physically to look over the side and down, but certainly very obvious to other ships passing close by. At sea chit chat on VHF between passing ships is universal as crews relieve boredom and check nearby ships that may have compatriots on board. A vessel seeing unusual “fixtures” on the side of a nearby vessel would most likely at least ask what they were for. The attack team therefore had to assume that post-first light the chances of their devices being detected would increase dramatically. On the morning of 13 June, first light was at 0427 hrs and sunrise at 0524 hrs. The timers will have been set, therefore, to detonate only a few hours after being planted.


The plethora of post-attack footage of the two vessels shows FTA with three distinct plumes of smoke emanating, presumably, from three holes in the ship’s side, and a single hole in the side of KKC, with a device (subsequently removed by the Iranians) about 3 foot above the waterline further for’ard. The presumption, therefore, is that 3 devices were affixed to FTA and two to KKC. Returning to the question of purpose and the added risk of detection from placing the devices on the side, rather than the stern of the target vessels, we must look at the respective cargoes, and the potential effect of the detonations. FTA was carrying 75,000 tonnes of naphtha, a highly volatile oil derivative with the characteristics of petrol and a flashpoint of -18°C. KKC was carrying 25,000 tonnes of methanol – effectively alcohol, less volatile than naphtha, but still highly volatile, with a flashpoint of 11°C. In effect both ships were floating bombs, and very big ones. The cargo is key to identifying the purpose of this attack, while noting the constraints imposed by the method and location. I.e. the IRGCN will have been well aware that the effect of their devices above the waterline would be significantly reduced and they therefore deliberately targeted two ships with cargoes of the greatest possible volatility. A cargo of diesel, or of crude oil, for example, would be very difficult to detonate and would likely have caused, if compromised, an ecological issue. It would have been reasonable to expect, even with the reduced effect of the limpet mines, placed directly against the hull inside which lay the cargo tanks, that the explosion would have penetrated those tanks and caused the detonation of the cargo. In that eventuality, as can be seen from footage of WW1/WW2 warships whose magazines have been compromised, the ships would likely have exploded instantly, breaking their backs and leading to their sinking in waters 400-500m deep.


Just consider for a moment the effect, and the likely response – two large tankers disappear in the early hours of the morning, following enormous explosions. Any evidence that survived the blast is now 500m below the surface inside the Iranian exclusive economic zone (EEZ). While the finger would still have been pointed at Iran, the outcome would have made deniability much more plausible. In fact, the current outcome challenges Iran’s denials and while nothing to date is conclusive, growing circumstantial evidence is reducing their ability to wriggle.


The question is why did the cargo fail to explode and I am not sure I can answer that, other than offer a few possibilities. Nevertheless, it is clear that crew members did not think that a subsequent explosion was out of the question, since both crews seemed very eager to abandon ships, neither of which has since shown any likelihood of sinking; they abandoned ship because they feared explosion. Since 1992 international Maritime Pollution (MARPOL) regulations have required tankers carrying environmentally destructive substances to be “double hulled” i.e. there must be at least two “skins” between the cargo and the sea. There is normally a buffer zone (“cofferdam”) between the hull of the ship and the skin of the cargo hold. Given that the force of the explosion will mostly have been deflected away from the hull of the ship, I suspect that the smallish device(s) had insufficient force to penetrate the hull, traverse the cofferdam and then penetrate the skin of the cargo hold. There may also be conditions/temperatures/safety devices built into the cargo hold, designed to counter the risk caused by the cargo’s volatility, that I am unfamiliar with, but that which provided sufficient protection to the cargo that prevented detonation. In any case, one of the devices on KKC failed anyway. Whatever the reason, the crew can be most grateful cargo detonation was not achieved; they would have died horribly.


That concludes my theory of what has actually happened. In summary – two ships deliberately targeted for the nature of their cargo, attacked by limpet mines attached by small craft in darkness and detonated on a timer a couple of hours later with a view to causing the cargo to explode (which failed), and the strategic intent of creating uncertainty in global markets.


So what does that mean for shipping? With two sets of attacks under their belts, the Iranians appear set on disrupting shipping, so these types of attacks are highly likely to continue. Again it will be the indirect approach with plausible deniability. I suspect that another attack within somebody else’s territorial waters, as with the Fujairah anchorage attacks of a few weeks ago, are unlikely as they carry a good deal of risk, but attacks on shipping transiting SoH and the GOO are very likely. Modus operandi will be similar to now. Insurance premia will likely rise considerably, and Lloyds may decide to apply a new high risk area.


In terms of protecting against the threat, shipping companies must immediately increase their lookouts, and have dedicated watchmen observing rearwards and down the flanks of the vessel, especially in darkness, while making passage between the SoH and through the GOO to the limit of Iranian coast. I would strongly counsel vessels taking a security team through the Indian Ocean (or returning from such a transit) to embark the team in their Gulf port of loading, unarmed, in order to do this task (or keep the unarmed team on board, after dropping off the firearms and kit at a Fujairah armoury). The professional security guards can perform these additional lookout duties without placing an extra burden on crew-members. Of course, if an IRGCN team is spotted in the approach, an unarmed lookout or security team has limited recourse to deter, but might hail on VHF (thereby alerting everyone in the vicinity) or call for military assistance. They could also fire flares, both in the air, and at the hostile craft. With an armed team, warning shots could be fired, which would likely sufficiently deter, but in the short term, until one of the armoury vessels relocates to the west side of the SoH this will not be possible.


More information will emerge in the coming days, which will either prove or disprove the theory above. If close to the mark, then this is a threat that can be countered with extra vigilance, especially when transiting the riskiest areas, or carrying the most explosive cargoes. I am sure there is more to follow.




Mark Gray is a Director of MNG Maritime Ltd, a company specialising in maritime logistics for the maritime security industry. Prior to establishing MNG Maritime in 2012, Mark Gray was a career Royal Marines officer, whose service included the command of a Royal Navy counter-piracy task group off Somalia in 2010.