SENSACIONES
8th February 2009, 08:08
Don Shirley's dive went smoothly at first.
He headed down quickly. About five minutes in, he reached 120m. He knew that Dave Shaw should now be returning to the shot line, beginning his long return to the surface, with or without the body. During an ascent, all rebreathers release some gas from the breathing loop to compensate for the reduced water pressure, so Shirley began to look for bubbles coming up the line.
He saw nothing. He wasn't too concerned at first. He thought that Shaw might have fallen slightly behind schedule on his descent. But when another minute or more went by and still no bubbles, Shirley knew that Shaw must be in trouble. As he dropped past the last group of four emergency tanks at 150m, Shirley began to prepare himself mentally: he was going to the bottom.
Some time after he passed 150m, Shirley glimpsed a single dim light below, at an angle off the shot line. But the light wasn't moving. Shirley – still plummeting – shone his high-intensity beam down towards the spot. If Shaw were conscious, he would certainly see it from this distance, and would respond by waving his own light.
The light didn't move.
This is bad, Shirley thought.
As he approached 220m, he still saw no bubbles and no movement from the light. He continued to descend, dropping about 10m every 20 seconds.
Past 220m. The light didn't move.
Past 230. The light didn't move.
Past 240. The smear of light in the blackness got bigger as he approached, but it hadn't moved since he first sighted it, nearly five minutes earlier.
Then, at about 250m, he heard a sharp crack down by his left forearm. Shirley glanced down, but he already knew what he would see: the Hammerhead [a closed-circuit, mixed-gas controller and decompression computer] was dark. It had imploded under the pressure of the depth and was now flooded, the electronics ruined.
In the space between heartbeats, a debate played itself out in Shirley's mind. For an instant, he thought that he might continue down the last 20m to the bottom. He could add oxygen manually to the rebreather loop. He might yet be able to do something for Shaw.
This was a contradiction of everything Shirley taught his students, everything that he believed. A critical failure always turns a dive. Always.
He thought: But maybe…
The dim light still wasn't moving.
Then: No. He's gone.
Now he had to save himself.
Shirley opened a valve to add gas to his wings, arresting his descent, then injected oxygen into the rebreather's breathing loop. But this spiked the oxygen to a dangerous level, so high that a single breath could have convulsed him. His next breath had to come from one of the open-circuit bailout tanks that floated at his left side. Shirley had simulated this emergency hundreds of times while training his students on rebreathers. Drills and skills, he lectured them. Now he went through the same procedure, reflexively: exhale, twist the mouthpiece valve to prevent water from entering the loop, remove the mouthpiece and let it float free, and bring the open-circuit regulator to his mouth.
The last part brought a quick twinge of uncertainty. The regulators on Shirley's emergency tanks were from the shipment of new Scubapro gear he had received in December. They were standard issue, not modified, and only briefly tested. As his right hand reached for the regulator on the nearest tank, Shirley was about to trust his life to a piece of off-the-shelf scuba equipment that had not been designed for these depths.
He fitted the mouthpiece between his lips and inhaled. Instantly gas flowed through the regulator, and he felt it fill his lungs. Less than half a minute after the emergency began, Shirley was stabilised. His descent was arrested and he was breathing safely. Shirley was now the only living being in the cave. Nearly 250m of water and 70 decompression stops lay between him and the open air. He began to ascend.
With the emergency averted, Shirley began to focus on a plan to get safely back to the surface as quickly as possible. The descent to 250m had increased his decompression dues – by how much he didn't yet know. He found that one of his two VR3 dive computers had flooded. But the backup unit was still operating and showed a decompression time of more than 11 and a half hours to the surface.
Shirley carried a thick set of plastic slates with half a dozen plans tailored for different depths and bottom times, based on schedules that he and Shaw had worked out in October. Each plan occupied two slates, and flipping through them was almost like paging through a book. Shirley decided to use a plan designed for three minutes at 270m. He hadn't quite reached 270, and he hadn't stayed for three minutes, but this would build in a margin of safety. The plan called for a first decompression stop at 222m for 30 seconds, and Shirley headed up, breathing from the bailout tank.
He checked the tank's gauge and discovered that the pressure had dropped perceptibly after just a couple of minutes. One breath at this depth consumed as much gas as 25 breaths at the surface. He could see the needle of the gauge tick downwards with each inhalation.
Shirley had brought two bailout tanks. He realised that at this rate, both tanks might be empty before he reached the emergency cylinders at 150m. The Hammerhead's secondary console was still operating – it monitored the machine but didn't control it – and when he checked the panel he saw that the oxygen levels in the loop had stabilised. He went back on the rebreather. This kept him busy: he constantly had to check the oxygen level in the breathing loop and add oxygen when the level dropped. He was also following the decompression plan, ascending in increments and holding for precise intervals. Shirley was now at the first set of emergency tanks. If necessary, he could complete his dive using only the cylinders on the line.
According to his original plan, he should have taken one of the three cylinders here and brought it with him when he continued up. But he decided to leave them all. Shirley still hoped that Shaw might be following him up the line. He knew it was unrealistic and could see only blackness below, but he couldn't completely reconcile himself to the certainty that he was leaving behind his dead friend.
Shaw might be alive, he thought. And if he was, then he would be facing a massive decompression, and he would need all the gas he could get.
He started up without the cylinder.
Lo Vingerling, one of the support divers, met Shirley as he arrived at 118m for a one-minute stop. Vingerling gave Shirley an OK sign – intended as a question – and Shirley promptly returned it. Shirley was so composed that Vingerling never realised that he was manually operating the rebreather. Vingerling only learnt of it a couple of hours later, when he finally surfaced.
Vingerling peered down below and saw only blackness. He was prepared to go down to 150 to look for Shaw; he had the proper gases and he was willing. He made a 'down there' gesture. But Shirley shook his head and drew a finger across his throat. Vingerling nodded. He pushed a valve to add gas to his buoyancy wings and began to rise.
The next support diver to drop down out of the darkness was Stephen Sander, about 18 minutes later. Shirley was now on a decompression stop at 81m. Sander was shocked to see just one light below as he approached Shirley. Sander knew from the look in Shirley's eyes that something was wrong. He also noticed that the controller on Shirley's left forearm had imploded and knew that Shirley must have gone beyond his planned depth.
Shirley made a pencil-on-paper scribbling motion, asking for a slate; he wanted to conserve his own. Sander gave him one of his plastic slates.
Shirley wrote: Dave not coming back.
Extract from 'Raising the Dead: A True Story of Death and Survival' by Philip Finch (HarperCollins)
He headed down quickly. About five minutes in, he reached 120m. He knew that Dave Shaw should now be returning to the shot line, beginning his long return to the surface, with or without the body. During an ascent, all rebreathers release some gas from the breathing loop to compensate for the reduced water pressure, so Shirley began to look for bubbles coming up the line.
He saw nothing. He wasn't too concerned at first. He thought that Shaw might have fallen slightly behind schedule on his descent. But when another minute or more went by and still no bubbles, Shirley knew that Shaw must be in trouble. As he dropped past the last group of four emergency tanks at 150m, Shirley began to prepare himself mentally: he was going to the bottom.
Some time after he passed 150m, Shirley glimpsed a single dim light below, at an angle off the shot line. But the light wasn't moving. Shirley – still plummeting – shone his high-intensity beam down towards the spot. If Shaw were conscious, he would certainly see it from this distance, and would respond by waving his own light.
The light didn't move.
This is bad, Shirley thought.
As he approached 220m, he still saw no bubbles and no movement from the light. He continued to descend, dropping about 10m every 20 seconds.
Past 220m. The light didn't move.
Past 230. The light didn't move.
Past 240. The smear of light in the blackness got bigger as he approached, but it hadn't moved since he first sighted it, nearly five minutes earlier.
Then, at about 250m, he heard a sharp crack down by his left forearm. Shirley glanced down, but he already knew what he would see: the Hammerhead [a closed-circuit, mixed-gas controller and decompression computer] was dark. It had imploded under the pressure of the depth and was now flooded, the electronics ruined.
In the space between heartbeats, a debate played itself out in Shirley's mind. For an instant, he thought that he might continue down the last 20m to the bottom. He could add oxygen manually to the rebreather loop. He might yet be able to do something for Shaw.
This was a contradiction of everything Shirley taught his students, everything that he believed. A critical failure always turns a dive. Always.
He thought: But maybe…
The dim light still wasn't moving.
Then: No. He's gone.
Now he had to save himself.
Shirley opened a valve to add gas to his wings, arresting his descent, then injected oxygen into the rebreather's breathing loop. But this spiked the oxygen to a dangerous level, so high that a single breath could have convulsed him. His next breath had to come from one of the open-circuit bailout tanks that floated at his left side. Shirley had simulated this emergency hundreds of times while training his students on rebreathers. Drills and skills, he lectured them. Now he went through the same procedure, reflexively: exhale, twist the mouthpiece valve to prevent water from entering the loop, remove the mouthpiece and let it float free, and bring the open-circuit regulator to his mouth.
The last part brought a quick twinge of uncertainty. The regulators on Shirley's emergency tanks were from the shipment of new Scubapro gear he had received in December. They were standard issue, not modified, and only briefly tested. As his right hand reached for the regulator on the nearest tank, Shirley was about to trust his life to a piece of off-the-shelf scuba equipment that had not been designed for these depths.
He fitted the mouthpiece between his lips and inhaled. Instantly gas flowed through the regulator, and he felt it fill his lungs. Less than half a minute after the emergency began, Shirley was stabilised. His descent was arrested and he was breathing safely. Shirley was now the only living being in the cave. Nearly 250m of water and 70 decompression stops lay between him and the open air. He began to ascend.
With the emergency averted, Shirley began to focus on a plan to get safely back to the surface as quickly as possible. The descent to 250m had increased his decompression dues – by how much he didn't yet know. He found that one of his two VR3 dive computers had flooded. But the backup unit was still operating and showed a decompression time of more than 11 and a half hours to the surface.
Shirley carried a thick set of plastic slates with half a dozen plans tailored for different depths and bottom times, based on schedules that he and Shaw had worked out in October. Each plan occupied two slates, and flipping through them was almost like paging through a book. Shirley decided to use a plan designed for three minutes at 270m. He hadn't quite reached 270, and he hadn't stayed for three minutes, but this would build in a margin of safety. The plan called for a first decompression stop at 222m for 30 seconds, and Shirley headed up, breathing from the bailout tank.
He checked the tank's gauge and discovered that the pressure had dropped perceptibly after just a couple of minutes. One breath at this depth consumed as much gas as 25 breaths at the surface. He could see the needle of the gauge tick downwards with each inhalation.
Shirley had brought two bailout tanks. He realised that at this rate, both tanks might be empty before he reached the emergency cylinders at 150m. The Hammerhead's secondary console was still operating – it monitored the machine but didn't control it – and when he checked the panel he saw that the oxygen levels in the loop had stabilised. He went back on the rebreather. This kept him busy: he constantly had to check the oxygen level in the breathing loop and add oxygen when the level dropped. He was also following the decompression plan, ascending in increments and holding for precise intervals. Shirley was now at the first set of emergency tanks. If necessary, he could complete his dive using only the cylinders on the line.
According to his original plan, he should have taken one of the three cylinders here and brought it with him when he continued up. But he decided to leave them all. Shirley still hoped that Shaw might be following him up the line. He knew it was unrealistic and could see only blackness below, but he couldn't completely reconcile himself to the certainty that he was leaving behind his dead friend.
Shaw might be alive, he thought. And if he was, then he would be facing a massive decompression, and he would need all the gas he could get.
He started up without the cylinder.
Lo Vingerling, one of the support divers, met Shirley as he arrived at 118m for a one-minute stop. Vingerling gave Shirley an OK sign – intended as a question – and Shirley promptly returned it. Shirley was so composed that Vingerling never realised that he was manually operating the rebreather. Vingerling only learnt of it a couple of hours later, when he finally surfaced.
Vingerling peered down below and saw only blackness. He was prepared to go down to 150 to look for Shaw; he had the proper gases and he was willing. He made a 'down there' gesture. But Shirley shook his head and drew a finger across his throat. Vingerling nodded. He pushed a valve to add gas to his buoyancy wings and began to rise.
The next support diver to drop down out of the darkness was Stephen Sander, about 18 minutes later. Shirley was now on a decompression stop at 81m. Sander was shocked to see just one light below as he approached Shirley. Sander knew from the look in Shirley's eyes that something was wrong. He also noticed that the controller on Shirley's left forearm had imploded and knew that Shirley must have gone beyond his planned depth.
Shirley made a pencil-on-paper scribbling motion, asking for a slate; he wanted to conserve his own. Sander gave him one of his plastic slates.
Shirley wrote: Dave not coming back.
Extract from 'Raising the Dead: A True Story of Death and Survival' by Philip Finch (HarperCollins)