Monday, June 05, 2006
Heavy metal: Diving the Iron Knight
By James Woodford
June 04, 2006
June 04, 2006
BERMAGUI, Australia -- Underneath Samir Alhafith was the kind of inky blackness that astronauts talk of when they first see space.
Alhafith and three others were swimming last Saturday in the open ocean at a depth of 125 metres, more than 12 nautical miles off the South Coast town of Bermagui. It was, by just a few metres, the second deepest dive ever undertaken in NSW waters.
Each moment in such an environment is critical but even so Alhafith allowed himself time to look towards the watery ceiling far above.
There was a small, porthole-shaped shimmering light, the bluish colour of last twilight. It was the midday sun filtered through a city-block's worth of seawater.
With an ocean on his shoulders, the less pressing of Alhafith's worries included being in the middle of a mako shark feeding ground, a known haunt for great whites, and the possibility of his support crew on the surface being hit by a southerly buster.
The real worry was the limit of human physiology. Within six minutes of free-falling from the surface, the divers' bodies were experiencing atmospheric pressures nearly 13 times greater than on the surface. Such a force turns air into a deadly and narcotic poison, making the body a laboratory of extreme chemistry.
Alhafith, Michael Kalman, Mark Eaves and Tony Keen, all Sydneysiders with regular jobs, were descending onto a giant freighter no person had seen since February 8, 1943. On that terrible day, the Iron Knight was sunk by a Japanese submarine. The ship was one of 16 vessels destroyed by Japanese submarines off the NSW coast during World War II. Only three of these have been found.
What makes the Iron Knight so significant is that it was the victim of one of the most infamous Japanese subs - the massive I-21, which also launched a float plane over Sydney during the midget submarine attack in 1942 and shelled Newcastle.
The four men belong to a group called the Sydney Project, which is dedicated to finding shipwrecks in deep water. So far they have made five highly significant discoveries. It was on another ship, also torpedoed by the Japanese off Bermagui, the William Dawes, that they logged the deepest dive in NSW - 135 metres.
Reaching such depths without a submersible is a highly technical achievement, involving careful calculations to determine how the human body and air interact under immense pressure. Such deep sea exploration is called technical diving and involves the use of special equipment and training.
Perhaps the most important item is the rebreather, which enables air to be recycled by scrubbing out exhaled carbon dioxide. Unlike regular scuba dive gear, rebreathers mean no bubbles are produced. Because oxygen and nitrogen become deadly at depth, the diver's tanks contain 75 per cent helium.
Theoretically there is no limit to how deep a person can swim if they adjust their gases and keep their rebreathers functioning. Practically, however, the biggest hurdle is decompression. A recreational diver spending an hour at 30 metres can get away with a five-minute stop at five metres to ensure any dangerous bubbles are dissolved in the blood stream. But after 15 minutes at 120 metres a diver needs to spend more than four hours decompressing.
There is no quick escape if something goes wrong - panic and make a rush to the surface from such a deep dive and your blood will fizz like a shaken soft drink with its lid popped.
Every minute beyond the calculated 15 Alhafith and his team might spend on the bottom would result in an additional hour of decompression. Considering the divers were already forced to while away the best part of half a day suspended in the open ocean, they kept strictly to their schedule. The entire time the divers were submerged the support crew bobbed exposed on the surface praying for good weather to hold. More than once, Alhafith has departed in millpond conditions and returned to the surface to find three-metre seas.
The rough location of the Iron Knight has never been a mystery. As David Jenkins wrote in his 1992 book detailing the Japanese submarine warfare against Australia between 1942 and 1944, Battle Surface: "Early on the morning of February 8, I-21 sank the BHP steamer Iron Knight (4812 tons), which was in a convoy of 10 ships 21 miles from Montague Island. The ship, which was carrying a cargo of iron ore from Whyalla to Newcastle, sank within two minutes, with the loss of 36 lives of her complement of 50. The merchant ships were being escorted by the corvettes, HMAS Townsville, which was on the starboard side of the convoy, and HMAS Mildura, which was to port. [Captain] Matsumura's torpedo passed directly under the 650-ton Townsville."
The ship might never have been found except that she fell onto sand in the middle of one of Australia's most economically important fisheries - the south-east trawl. It has probably been snagging nets for decades. But it was a Bermagui skipper known as Rocco "Rocky" Lagana who recorded the torpedoed ship's exact location. Both his father and uncle snagged nets on the sunken ship and warned Rocky to keep away from it.
"It comes up five fathoms from the bottom on a depth sounder - it really marks solid," Rocky says. "I knew she was a good one."
Lagana passed the information onto local fishing charter operator, Keith Appleby, who searched the spot with his sounder.
"I can vouch for a few fishermen who have lost nets there over the last 35 years," Appleby says.
Last Saturday the dive expedition departed Bermagui. Once over the site a shot line was dropped to the bottom, aimed to land just to the side of the targeted spot. Attached to that line were two shark pods, emitting an electric pulse with a range of 15 metres, designed to keep man-eaters at bay while the divers decompressed. Also connected to the line were two extra cylinders of air - one a nitrogen/oxygen mix and a second, pure oxygen.
As a back-up, on board was a second decompression line, identical to the first. In the event one of the divers got separated from the rest of the team, he could send up an inflatable buoy and a message requesting the emergency line be sent down.
Facing the prospect of hours in 14 degree water, the divers donned dry suits and spent about 10 minutes five metres below the surface, where they did a last check to ensure all the gear was functioning correctly. After the plunge to the bottom one pair of divers took a line to the vessel to make sure no one got lost. The second pair began to search for any clues which might confirm the identity of the wreck.
Alhafith says he yelled with joy to himself when he saw it was a shipwreck. "A lot of times we don't know whether it will be a wreck or a rock."
Visibility was excellent - more than 20 metres for the entire dive.
He and his team touched down in full view of the bridge. The ship looked as though it had been snap frozen, little changed in spite of being underwater for more than half a century. Although more than 140 metres long the ship was intact, Alhafith says. The divers also confirmed the legends of generations of snagged nets are not apocryphal.
"The most spectacular thing was not just the sheer size of the wreck but the menacing look of the fishing nets draped and snagged over the bridge," he says. "The nets seemed to be everywhere and were hanging, suspended by fishing buoys attached to lines."
The fact the bridge was in the centre of the ship was the first clear indication the wreck was the Iron Knight. Cargo holds were both forward and aft of the bridge. "The holds were absolutely enormous," Alhafith says. "Like huge black pits." One side of the ship seemed to have folded in on itself and the team suspects that may be the spot where the torpedo struck. Unfortunately no name plate, bell or other definitive identifying feature was found.
The quarter of an hour of exploration was quickly over and the team had to begin their lengthy decompression ascent. The first stop was half a minute at 102 metres, increasing to 77 minutes at 4.5 metres.
The dive was so lengthy and the air so dehydrating that the men needed to drink from special bladders with tubes during their decompression. Alhafith went through three litres of energy drink during the 4½-hour dive.
During the final hours of the decompression the team was supported by four divers using regular scuba gear who assisted with bringing equipment to the surface. It is during the decompression part of the dive that the team usually has its best wildlife encounters.
On previous dives killer whales, dolphins and seals have all swum in to see what the divers are doing. Last weekend a sunfish - two metres long and three metres high - stayed with the divers for over an hour. "It was like watching a documentary," Alhafith says. "Seals have come right up and seem to be sniffing us.
"Some people want to just see rust but for me it is seeing an untouched ecosystem. You see marine life which is amazing. The wreck is like a museum and you are the first person to see it. It's like opening an Egyptian sarcophagus.
"The wrecks in shallow water have been stripped. Technical diving is all about exploring, going where no one's gone before."
A maritime archaeologist with the Heritage Office, Tim Smith, agrees that based on the size and location of the wreck, it probably is the Iron Knight.
"Because of the depth it has been protected and it is therefore archaeologically intact."
Government occupational health and safety rules forbid him from diving to such extreme depths, which means he and other researchers are completely dependent on amateur adventurers to plumb the ocean in search of wrecks.
Even if he was allowed, Smith says he would not undertake such a hazardous pastime. "Those guys are right on the edge of the envelope."
Despite keeping technical diving at arm's length, the Heritage Office has put the Sydney Project's divers through some of its maritime archaeology training. Most critical to Smith is that the wrecks remain undisturbed and nothing is salvaged. "This project has provided a tantalising glimpse into Japanese naval activity off our coast during World War II," he said.
In three weekends the team will return to the Iron Knight - this time with underwater scooters so they can circumnavigate the vast wreck site.
There have been at least three deaths in NSW from deep diving but so far no one from the Sydney Project has been harmed.
Samir Alhafith says simply: "Touch wood."
SOURCE - Sydney Morning Herald