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A crate of shells aboard Thistlegorm.

 

ALWAYS LIKE TO ASK my students what they do for a living. It might indicate how they will fare on the diving course.
Pilots are often the best, because of their nice mix of practical and academic training. The armed services are pretty good too, and they always do what theyre told!
The police take lots of notes, and the clergy just pray that the Almighty is watching over them, and probably me.
Im a bomb disposal specialist, says Peter. I decommission ammunition dumps and clear unexploded ordnance. You could say Im the one who clears up the mess after the wars are over.
Peter Le Sueur had signed up for a decompression-diving course. The mess means unexploded bombs, and hundreds of rounds of live shells or landmines, sweating dangerously in the heat of foreign deserts.
Peter started in ordnance clearance as a technician in 1972, and has been nose to nose with thousands of the worlds deadliest explosives for more than 35 years. He has worked in all the hotspots - Afghanistan, Kuwait during the first Gulf War, Iraq, Cambodia, Mozambique, Sudan and Nepal, and is now in the Balkans, ecommissioning munitions dumps in Montenegro.
In many professions the consequences of error are the missing of a deadline, loss of a sale or damage to a product. Even in technical diving there are often multiple safety procedures in place before things go terribly wrong.
In Peters job, error means instant death, not just your own but possibly that of many others in surrounding acres. He showed me a recent photograph of an Albanian arms dump that ignited prematurely, leaving a 178m-long crater. There used to be buildings on that spot. Anybody even close to that explosion would have been completely vaporised.
I asked him what type of bombs he had dealt with. Grenades, mortars, artillery shells and aircraft bombs weighing up to 2000 pounds, he told me.
And what interested him about decompression diving Im very happy to look at reefs and marine life, but my real interest is in shipwrecks. Some of them are outside recreational diving limits, so Im acquiring the skills and qualifications for deeper and longer dives, which means learning to use twin tanks and carrying decompression gas.
I asked Peter if the attention to details required in bomb disposal had been useful in learning to tech-dive. Yes, needless to say theres no cutting corners or taking short cuts in my job, he replied. I think thats important with tech diving too. Failing to prepare properly or ignoring safety protocols can lead to disaster.
Its as safe as you want it to be. The choice is in your hands, and nowhere else. If you train properly and do what youve been taught, youll live longer.
Have you ever had a close call in all your years of bomb-disposal work I asked.
Yes, I was injured while disarming a Chinese grenade. The fuse functioned unexpectedly and I was just able to toss the grenade a short distance before it exploded - but not far enough to be out of the lethal killing area.
Peter rolled up his Che Guevara T-shirt to point out half-a-dozen entry wounds resembling centipedes.
The legs are the old stitch scars.
The surgeons werent as cosmetically considerate in those days, he chuckled. They removed 23 ball-bearings from my legs, arms and body; the scars are mostly caused by the emergency surgery which was necessary to find them.
Together Peter and I visited the Red Seas premier icon wreck. Thistlegorms cargo contained hundreds of tons of munitions destined for the British 8th Army in North Africa.
Peter had dived Thistlegorm as a recreational diver, but this time he had twin tanks of 36% nitrox and a 50% nitrox decompression stage bottle. With more than 80 minutes to play with, he was interested in only one thing - the bombs.
How did you find looking at hundreds of live shells and bombs lying around under water I asked him after the dive.
Very, very interesting. I was able to identify a whole variety of munitions, from mines to massive 15in shells weighing almost 2000lb. Ive defused aircraft bombs weighing up to 2000lb, but never under water. The shells on Thistlegorm are mostly of the armour-piercing type, some with delayed fuses so that the explosion occurs inside the ship theyve hit.
I had watched Peter swim among the munitions, studiously observing the deadly relics of an era in which most of the worlds great minds were dedicated to grand-scale destruction. Their work would keep him employed for decades to come.
Like the Merchant Navy crewmen on Thistlegorm who perished when it sank, bomb-disposal experts are also unsung heroes in warfare.
The 5ft-long thin, cylindrical tubes are sea-mines, Peter told me. Theres one smack under the bow, then half a dozen lying on the floor near hold four on the port side.
These were often dropped by aircraft and would sink to not more than 50m, where they would rest on the bottom. The idea is that they would blow up when a ship went overhead. Its very likely that they were for use in North Africa on the Mediterranean coast.

I MENTIONED THE MANY open cases of shells, often stacked in fours. Theyre the 4in shells probably used for guns like the type on the aft deck. That will be the smaller of the two guns. The one nearest the stern is 4.7in calibre and would take the larger rounds we saw in hold five.
The big boys are the 15in shells, which would have been intended for battleships or battle-cruisers similar to HMS Hood. She was involved in the battle of Denmark Strait against the Bismarck.
Peter studied our underwater photos of the two monster shells. They had a range of 22 miles and could knock out destroyers, pillboxes or coastline defence systems or, of course, other battleships or battle-cruisers.
Divers have often asked why the Thistlegorm didnt blow up immediately, with all that ammunition on board.
Half of it seems to have survived the strike, the resulting fire and, finally, the explosion in hold four. Surely a chain reaction would occur and blow everything up
Generally, the 4in shells wouldnt have exploded in mass, said Peter. We can see that some are intact and some arent. Theyre strewn around the seabed and across the remains of hold 4.
If the ship had been filled with aircraft bombs, which contain a high proportion of HE (High Explosive) and are thin-cased, or anti-tank mines, the whole lot would have gone at once.
The crew who survived did so because of the type of cargo.
Records and survivor witness accounts indicate a gap of around 15 minutes between the bombing and the secondary explosion that blew Thistlegorm in two. This gave the 32 survivors time to escape the big detonation of munitions.
They spoke of being sprayed by small-arms rounds going off in the fire, though few were injured by the flying bullets. Why
When fired from a rifle, the propellant gas is behind the bullet, so its coming out at about 2500ft per second, Peter told me. That would penetrate several millimetres of metal.
In a blazing fire, you wouldnt get even a quarter of the propulsion force of a bullet fired from a rifle, but brass fragments from the cartridge case would be discharged as the cartridges cooked off in the fire. The likelihood of a bullet penetrating a body is much, much less.
Do you reckon Thistlegorm is safe for divers I asked. There are still a lot of live armaments lying around.
The chances of anything going off spontaneously, or even by a severe impact, is small, said Peter.
Many of the shells down there are unfused, and the fuse is the most sensitive part of the projectile. Even when fused, these bombs have many safety mechanisms to prevent accidental detonation. The primers are at the bottom of the cartridge, which propels the shell from the gun, and many would have broken down as seawater came in.
On land, if you give a primer a heavy tap with a sharp object it would probably fire. Under water its been there so long that its less likely.
With armour-piercing battleship shells, of the type found on the Thistlegorm, the fusing mechanism is inside the shell and they detonate only on impact, after penetrating the side of a battleship. Theyre pretty safe.

THISTLEGORM IS NOT A DEEP DIVE at 30m, but on air recreational divers can spend only 20 minutes without any decompression obligation. Our chosen depth was 28m, allowing us to survey the stern section and the munitions around the bombed-out area of hold four.
We chose a 50min bottom time plus 15min at 18m breathing 50%, which gave us a good stretch at the bow and upper decks. Such was the nitrogen washout that by the time we reached 9m our computers had cleared.
Even after a 10min courtesy stop at 6m we surfaced with 75bar of back gas and half a tank of decompression gas. Who says tech diving is dangerous
Peter has booked himself onto a Jack Ingle wreck trip to the South China Seas.
I want to visit HMS Repulse, which is below 40m and definitely a decompression dive, he said. Surprise - its also full of guns and bombs!

John Kean is author of SS Thistlegorm - The True Story of the Red Seas Greatest Shipwreck (Underwater World Publications).


Is
Is it ticking Bomb-disposal expert Peter Le Sueur at Ocean College between dives.
Markings
Markings on a 4in shell from a crate aboard Thistlegorm. These were used in the anti-aircraft guns on board.
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One of the 4.7in shells from hold five. These would have been used by the gun nearest the stern.
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