Aircraft Carrier HMS Hermes, Short History & Dive Report

09 April 1942 11am –With her covering fighters and obsolete torpedo/bomber biplanes ashore, dispersed to airfields and then destroyed in earlier Japanese air raids over Ceylon, the Carrier HMS Hermes’ three high angle 4.5’ anti-aircraft guns, and six 20mm cannon were quickly overwhelmed & knocked-out . . .and she sinks rapidly after 40 or more direct hits by 70 Dive Bombers. 307 men are killed in a battle lasting only fifteen minutes. In the course of events of that tragic day however, the action, suffering and sacrifice of the men of the Hermes would become obscured and forgotten, relegated to a minor footnote in history by another campaign’s catastrophic ending and coincidence: The headlines around the world chronicling instead the unconditional surrender of 72,000 US & Filipino Troops, the Fall of the Philippines, and what would become the infamous Bataan Death March. . .

09 April 2010 11am –68 years to the day & hour, I’m in an airliner flying over the near shore Sri Lankan east coast. In my mind, I can imagine just below me, seeing wave after wave of Japanese Val Dive-Bombers scoring hit after hit –essentially an unopposed target practice run --and the smoking hulk slipping beneath the surface. As an avid WWII Pacific history buff and technical wreck diver, I hoped the coincidence of my first time visit to this little island nation and the Hermes Wreck along with the battle that sunk her exactly 68 years ago would not be a bad omen.

Seven hours by van coach, on the next day, to drive the entire width of the country coast to coast –from the Int’l Airport & capitol Colombo in the west to Batticaloa where the dive operator Sri Lankan Diving Tours has its east coast facility. Two-lane hwy all the way, one lane each direction. Not only do you have to watch out for oncoming traffic while passing, but also for pedestrians (no sidewalks), and the usual animals --cattle, goats, dogs, chickens . . .along with the unusual --wild & domesticated elephants (there was a headline in the news that week about a wild elephant that attacked a motorized tricycle taxi and threw it down an embankment, the occupants escaped without injury). The farther you get towards the east, the more army checkpoint bunkers you start to see, as this area was formerly contested ground between Gov’t Forces and the Tamil Insurgents only a few years ago. During impromptu “relief” breaks off the side of the road, me and my fellow divers were told by the van driver not to go out too far because of landmines (we thought he was joking).

Crossing over Batticaloa Lagoon on the picturesque Kallady Bridge, we arrived at a dusty but charming compound called the Riviera Resort. Lonely Planet noted that the resort had the best accommodations and was popular with NGO’s (Non-Gov’t Organizations), and sure enough we saw a few Red Cross/Red Crescent vans in the compound, along with some UN vehicles with “MINE” warnings labeled along the sides. After eating a late dinner (delicious curried anything & everything: I could easily become a vegetarian eating Sri Lankan or Indian food), we proceeded to the dive ops to set-up gear.

Me and five other divers, regular clients of Tech Asia Puerto Galera Philippines, were the first large tech diving group to visit the Hermes since the end of the Sri Lankan Civil War last year. The dive ops center was still unfinished, in an on-going state of construction, so we kitted-up in what was used as a temporary compressor/gas blending building. Without any air conditioning, the hot & noisy compressor running and gas blending going on, we proceeded to put together our gear in a small room which quickly became a combined sauna and bikram yoga session, as we adjusted & manhandled our doubles & deco tanks on the floor without any tables or workbenches. The doubles for backgas were the standard 11L/AL80 twins, bands and DIN isolating manifold, but the deco bottles supplied turned out to be a 11L/AL80 for nitrox50, and a 9L/AL63 for Oxygen. Both my deco bottles had yoke valves, so I had to use a DIN to yoke adapter (more on that later).

The dive days for the next two weeks of my trip would begin with breakfast at 7am, followed by a van or boat pick-up at 8am bringing us to the dive op center. The van ride was along the coast were the devastation wrought by the 2004 Indian Ocean Tsunami was still visible: row-upon-row of bare and upended concrete foundations. Two thousand people either died or went missing within the few kilometers area that we drove through. The boat ride through the lagoon was just as sobering: what looked like the occasional floating log on the surface were actually salt water crocodiles, which decided to stay around after feasting on the Tsunami victims back then. We would then get to dive center by 830am, gear & load up, and motor out to the Hermes divesite GPS coordinates by 930am, still within sight of land and the lagoon’s lighthouse. Felician, the dive op manager would use a depth/fish finder to spot the wreck, and throw in a grappling hook to anchor on and tie-off the line to the lead skiff.

The surface current was moderate to strong; the lead skiff tied-off stationary to the grappling hook downline still looked like it was making 2knots headway as the current coursed around its bow, leaving a wake behind the stern. Those divers in the lead skiff would carefully mount-up their doubles & clip on deco bottles, keeping the boat in balance, and then back flip drop over the gunwales simultaneously into the water, surface hauling themselves hand-over-hand forward on granny lines towards the bow downline. Those on the other skiffs would drop in up current and drift back toward the bow of the lead skiff and hopefully intercept the downline as they flew past on descent.

Just the physical exertion, pulling yourself along the surface with 11L doubles with 11L & 9L deco bottles clipped on, and then down another 5min of pulling hard hand-over-hand on the downline to depth at 48m was enough to blow through 50bar of expensive 21/35 trimix backgas. We thought about bringing an extra stage bottle each of bottom gas to offset this, but decided not to use it fearing our limited supply & unreliable transport delivery of helium would not last us through the week. Visibility was variable with initial good clarity in the first 15m, but would start getting hazy going deeper, and then beyond 33m the ambient light conditions would darken considerably as the wreck came into view. At 48m, shielded from the current in the lee of Hermes’ hull, the viz range varied as much as 3m to 9m in very dark murky water.

The dive planning tactics and strategy that developed over the first couple of days involved taking 50bar right out of backgas calculations all together due to fighting the current as described above. Setting aside a MGR (Minimum Gas Reserve) of 70bar in backgas, meant we only had 80bar out of a total of 200bar backgas to explore the wreck externally. Internal explorations used the modified rule of thirds –take one-third of 80bar, and you get 26bar delta turn pressure-- which at an average depth of 48m translates to 5min penetration time, possibly 10min if you can somehow recover and slow your breathing rate down after working hard descending hand-over-hand on the downline. Typically, I would get to the entryway with 150bar reading, and turn the penetration after 5min and 125bar showing on the SPG, but as the week progressed, I was approaching 10min and turning it around at 120bar as we became more physically “acclimated” and familiar with navigating our temporary main line.

The deco profile was generated using the Ratio Deco Method, 1:1 schedule with nitrox 50 as intermediate deco gas, and optionally utilizing Oxygen as the final gas to clean-up residual inert helium and nitrogen. Planned bottom time was 25min at an average 48m depth on 21/35 standard gas, so the combined intermediate and final gas deco times added up to 30min, and the deco stops were linearly prescribed this way: gas switch at 21m to nitrox 50: 4min@21m; 3min@18m; 3min@15m; 3min@12m; 2min@9m (nitrox 50), 2min@9m (backgas break) [note: no S-curve shaping]. Gas switch at 6m to Oxygen: 12min@6m and a 1m/min ascent to surface on O2. Deep stops started at 36m (2sec pause); and 1min hard stops every 3m up until the nitrox 50 gas switch depth at 21m. Total time of dive ranged from 70 to 80min with minor extensions on-the-fly to the bottom time and base deco schedule above. Gas usage over a SCR (Surface Consumption Rate) range of 10-15L/min turned out to be 800L of nitrox, 500L of O2 and 3400L of 21/35 bottom mix. Drifting deco protocol with the SMB deployed at 21m after the nitrox 50 switch. Surface Interval between the morning and afternoon dives was at least three hours.

Because of the heavy deco tanks (AL80 or 11L bottle for nitrox 50, and AL63 or 9L bottle for Oxygen), we would fully clip off only one bottle in standard position (clip-off at the left shoulder d-ring and left hip d-ring), and nose clip the other bottle not being in use to the left hip d-ring: during the first initial deco gas switches, I tried keeping both in front after switching to O2 at 6m (i.e. not fully un-clipping the AL80/11L bottle from standard position and rotating it back to nose clip on my left hip d-ring), and my overall trim went to hell (my buddy thought I was signaling “look at the Manta Ray” when he saw me flapping my arms, sculling & trying to regain balance from a head stand). Deco switches were verified per standard procedure, but additionally because of the DIN/yoke adapters, you had to visually identify that you were turning open the correct deco bottle valve knob instead of mistakenly unscrewing the adapter!

The marine life on Hermes is the most prolific I’ve ever seen on a wreck; probably equivalent to a Truk Lagoon circa 1980’s when it was just starting to be re-discovered again by the recreational dive industry. Large schooling Trevally, Jacks and Tuna. Huge foot long, thick & “girthy” Lion Fish, the largest I’ve ever seen (shine your primary light at them, and they just flare their spines and look at you like “so what?”). The lead guys on penetration twice saw a gigantic monster Grouper inside the Hanger Deck that scared the holy crap out of them (said it was so big that if it wanted to, it could’ve easily swallowed a person whole). Lots and lots of your usual tropical fish: damsels; basslets; surgeons; fusiliers, bannerfish; snappers and sweetlips etc. Beautiful colorful anemones, sea fans, gorgonian and black corals encrusting the wreck, all big and a full sixty-eight years worth of growth undisturbed –that is until we came along and started grappling onto the wreck (one of the big criticisms and number one priority IMHO --a permanent mooring line should be installed nearby ASAP, similar to the mooring system in Truk, in order to preserve and protect the coral growth, as well as help divers locate and descend on the wreck).

HMS Hermes herself is capsized over to port, her Bridge/Island Superstructure on the starboard side now smashed, bent outward and partially buried in seabed mud as she turned over and settled into the bottom (the Ship’s Bell is probably in the vicinity underneath all the rubble, but we couldn’t find it). Her bow faces south into the current; her rudder and two of her screws the most prominent and easily recognizable reference point. Challenging initially to navigate externally, you orient yourself starting at the screws or the keel: if the keel is on your right and the flight deck is toward your left, then you are traveling south towards the bow. Internally it’s extremely disorienting at first and treacherously hazardous to penetrate because of her inversion (i.e. floors are now ceilings and ceilings now floors). The tight engine room spaces were terrifying to look at from outside the catwalk access hatchway: The boilers, engine cylinders, reduction drive gear and shafts were all hanging there upside down just waiting to collapse and crush you. The expanse of the hanger deck, basically a large cavern, was inviting to exploration, but also was probably filled with a lot of debris from bomb damage, munitions magazine & fuel explosions, and other potential entanglement hazards. We simply didn’t have enough backgas to safely explore such a wide area that would have pushed deeper the average depth to 51m (starting to think about CCR training for that MC90/160 again. . .).

In short, looking back over the two week expedition, I’m glad I prepared beforehand with physical training –lots of lat pulldowns & row machine exercises in addition to a regular weightlifting and running regimen-- or I wouldn’t have endured the heavy current dive conditions, and the activity in the intense heat & humidity of the region. This was the farthest I’ve ever traveled, literally half-way around the world from Los Angeles (exactly 12.5 hours ahead of Pacific Daylight Savings Time); and the 19 tech dives to 48m were the most two-bottle mandatory deco dives I’ve ever done consecutively on a single divetrip. It definitely wasn’t a typical relaxing scuba vacation trip to the tropics, but still a good time in remote hardship camaraderie with a fun group of very skilled technical wreck divers.

Finally from a historical viewpoint, it is a solemn and moving experience to dive HMS Hermes, the only dive-able Aircraft Carrier of WWII sunk-in-action. In retrospect its sinking marked one of the longest most successful strategic sorties in naval history, 8000 miles in five months by Admiral Nagumo's Fleet from Pearl Harbor Hawaii to Ceylon (Sri Lanka), as well as the zenith and the beginning of the end of The Empire of Japan. She would turn out to be the last one-sided loss of an allied aircraft carrier without exacting a cost in kind or greater from the Imperial Japanese Navy. Hermes’ redemption and the final revenge on the three carriers who launched planes against her --and on the US Pacific Fleet at Pearl Harbor-- would come just two months later in June, at the Battle of Midway. . .

http://www.srilanka-divingtours.com/

Hermes 2010.pdf

Teammate Mike Barrow's Hermes picture album:

http://picasaweb.google.com/118343039486425882607/DivingHMSHermesAp...