Diving the Atlanta wreck
For the first time in the four years since my own dive on the USS Atlanta, which at the time was the deepest wreck dive by a woman anywhere in the world, divers have revisited the wreck, lying on the edge of Iron Bottom Sound off Guadalcanal in the Solomon Islands. Using closed circuit rebreathers, or CCRs, Kevin Denlay and Peter Frith dove the sleeping giant on 26 April 2002. This was the first time that CCRs had been used on the Atlanta and the expedition itself was the first devoted entirely to the use of CCRs for technical diving in the Solomon Islands. As the dive was rather an â€˜impromptu eventâ€™ late in the expedition they did just one dive to 115 metres/378 feet on the shallower stern section of the wreck. Peter Frith used an Inspiration CCR whilst Kevin used a Mk15.5 CCR and a Silent Submergence UV-18 scooter for transport.
â€˜We hadnâ€™t gone to the Solomons with the intention of diving the Atlanta but everything was going so well that on the second last day of our expedition it just came together. Four years had passed since I or anyone else last dove on her so it took a while to line up the marks, but we got her,â€™ Kevin said. â€˜It was also Peters first time on the Atlanta so we were aiming for the â€˜relativelyâ€™ shallow stern area (rather than the deeper bridge/bow section that reaches 130 metres/430 feet) and although the shot line landed out off the hull side of the wreck (she lays on her port side) it turned out it was almost adjacent to the starboard five inch dual waist mount, an area with which I am very familiar. Having the scooter for transport I rode up to the break in the stern, the shallowest point at around 100 metres/330 feet, but the visibility was rather poor, way too poor for wide angle photography, so I didnâ€™t continue on over to the separated stern section which had been my target. After a while I scootered back and found Peter inspecting the decimated waist mount and then motored a little farther forward, almost to the torpedo hole in the hull, before terminating the dive as the visibility had continued to deteriorate. Returning to the general area of the shot line it was reassuring to see the Sea Blitz strobe I had set on the down line flashing in the gloom, guiding our way home. It was a shame about the visibility as the light level was relatively good and there was no current.â€™ The divers used a heliair diluent of trimix 8/62 (8% oxygen, 62% helium) in their rebreathers which gave an equivalent narcosis depth of 37 metres/123 feet at 115 metres/378 feet.
Both divers also used VR3 mixed gas computers to control their closed circuit decompression schedules and after spending 15 minutes on the bottom were out of the water a little over two hours later. They kept their bottom time intentionally short as they did not have enough open circuit bailout gas or the support divers needed for safely completing longer deco times with correspondingly higher CNS (central nervous system) oxygen loadings. â€˜As it was the new helium algorithm in the latest version of the VR3 (as used in Proplanner Decompression Software) shaved almost 40 minutes off the deco we would have done if we were still using the Proplanner deco schedule we used four years ago. Of course we werenâ€™t diving CCRs four years ago, so that was a bonus, but itâ€™s an interesting comparison on where decompression theory is headed.â€™
Kevin did 17 consecutive days of CCR mixed gas diving on this Solomons expedition, two dives a day some days, one on others, all with extended deco and all using gas (helium). â€˜This was the first time I had used my CCR in the Solomons and I have to say that of all the expeditions I have conducted there this was the best I had felt physically at the end of each dayâ€™s diving. Neither Peter nor I bothered to change to air diluent for the shallower afternoon dives. On all our dives we stayed on gas until the 6 metres/20 feet deco stop and then flushed the rebreathers with oxygen so the final stops were done on almost pure oxygen. We didnâ€™t even bother with a deeper air flush. Dived correctly helium is your friend, not nitrogen.â€™ In those 17 consecutive days of mixed gas CCR diving Kevin used only 1700 litres, or approximately 60cf of helium in his diluent, less than what just one deep dive on open circuit would require! â€˜To do the dives we did on open circuit in the Solomons would have been relatively expensive and require extensive gas mixing each evening. A CCR might seem an expensive investment up front but a few expeditions or dive trips of this nature and it pays for itself.â€™
The divers stayed at the recently refurbished Vanita Lodge on Tulagi Island and dove with the new proprietors of Solomon Islands Diving, also now operating from Tulagi across Iron Bottom Sound from Guadalcanal, and had nothing but praise for their land based operation. Beside the USS Atlanta they also dove the USS Aaron Ward (a destroyer), USS Kanawha (a fleet oiler), USS John Penn (an attack transport), HMNZ Moa (a subchaser), four individual Japanese â€˜Mavisâ€™ Kawanishi flying boats, the huge Japanese transports Azumasan Maru and (the deep and rarely dived) Sasako Maru, and the recently rediscovered Tama Maru. (*See sidebar for wreck details)
For more information on the fantastic diving on offer in the Tulagi/Guadalcanal area contact Neil at Solomon Islands Diving on 677 32144 or at firstname.lastname@example.org or Kevin himself at email@example.com.
Taking into account that this was the first time CCRs had been used for technical diving in the Solomon Islands, and given the â€˜remoteâ€™ nature of the expedition, the two divers shipped in all their own equipment including helium, Co2 absorbent, a Haskel booster pump, fill whips/filters, extra CCR cylinders, In-water Recompression Kit, etc, etc. Altogether they freighted up 374kg of gear from Australia, and took another 115kg with them on the plane! Other necessary support gear (deco cylinders, down lines, surface buoys, deco bars, etc) were already stored up in the Solomons from Kevinâ€™s previous expeditions. Given the above, it is imperative that anyone thinking of visiting the Dive Tulagi operation for either serious technical or CCR diving need to contact them well in advance so critical items needed (helium, Co2 absorbent, etc) can be put on station in time to support any proposed trip.
by Kevin Denlay
The USS Atlanta CL-51, a 540ft / 8000+ ton (loaded) purpose built anti-aircraft cruiser launched in 1941 was the first of the Atlanta class cruisers. Her armament as launched consisted of sixteen 5" guns in eight twin mounts, three quadruple 1â€™1" AA guns, six 20mm machine guns, two quadruple torpedo tubes and two depth charge racks with six depth charge throwers. Under battle conditions she had a complement of approximately 800 men. (At the time of her sinking she had additional 1.1" and 20mm AA guns)
In her short operational career she served at the Battle of Midway, supported the initial landings at Guadalcanal/Tulagi, participated in the carrier battles of the Eastern Solomons and Santa Cruz, and of course the wild melee known as the Naval Battle for Guadalcanal that lead to her demise. Although not built to fight battleships, that is exactly what she found herself facing on that fateful night some 60 years ago. She was the flagship of Rear Admiral Norman Scott at the time of her sinking on Friday, 13 November 1942 and had been the lead ship in the cruiser column that night.
Struck amidships by at least one of the feared oxygen powered, high explosive â€˜Long Lanceâ€™ torpedoes fired by the Japanese destroyers Ikazuchi and Inazuma and deluged with more than 50 medium and large calibre shell hits - some of them from â€˜friendly fireâ€™ - she was the scene of much carnage. In all 172 brave men were killed, including Admiral Scott and all his staff on the bridge bar one. Although still afloat when morning came the Atlanta was scuttled later that day, after all efforts to save her proved futile, in Lunga Roads off Honiara, Guadalcanal. She now rests tilted well over on her port side with her stern severed where the scuttling charged was placed and the gaping wound from the torpedo hit clearly visible under her hull.
For her part in the action that night USS Atlanta was awarded the prestigious Presidential Unit Citation and Admiral Scott a posthumous Medal of Honour. The night battle that she fought in on 13 November 1942 is now widely regarded as a critical junction in the Pacific Campaign and the turning point that swung the odds in the allies favour in the six month long struggle for Guadalcanal.
The USS Atlanta was first dived on 30 November 1995 by Terrence Tysall and Kevin Denlay with the objective of laying a plaque in honour of her gallant crew.
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