November 13th, 2006
San Pedro de Atacama, Chile
We were back in San Pedro de Atacama over the weekend for the dive team to do its final pre-dive training. The purpose of this training is to do what Randy Berthold, the diving safety officer for the expedition, refers to as "an end-to-end system test." In other words, the dive team did a practice run in real time - putting on their dry suits, assembling their gear, getting into the water, performing sample-collection and photography tasks - just as though they were in the summit lake on Licancabur. Except they were actually in a hotel swimming pool in San Pedro.
Unfortunately, Randy will not be able to make the ascent to the summit lake. Instead, he'll be performing his role as diving safety officer, staying in touch with the dive team by two-way radio from the refuge at Laguna Blanca. Eric will take over Randy's on-site co-ordination role on the mountain. And other members of the team will be shifting around their responsibilities to cover tasks that were originally assigned to Eric. So everyone came to San Pedro to do a complete run-through, practicing their new roles. Rehearsing these new roles until they are second nature is important, because at high altitude it sometimes becomes hard to think clearly. Rob compares this rehearsal process to an actor rehearsing his role before going on stage. The San Pedro pool test is the dive team's dress rehearsal.
There is a precise and detailed protocol that the divers will need to adhere to if their dives are to be successful - and safe. One of the most important of these is assembling their "scrubbers." A scrubber is a component of a "closed-circuit rebreather," the special scuba equipment they will be using. Unlike normal scuba gear, in which divers carry tanks of compressed air on their backs, the High Lakes dive team will use more compact units that contain pure oxygen.
When you exhale after taking a breath, you exhale oxygen as well as carbon dioxide. The material in the scrubber reacts chemically with the carbon dioxide, pulling it out of the diver's airflow, and allows the unused oxygen to recirculate. It's important that the scrubbing unit is assembled carefully so that it functions properly. Otherwise, serious medical problems can occur. And although preparations have been made for dealing with any medical problem that does occur, whether dive-related or not, it's something you'd definitely rather avoid when you're on top of a 20,000-foot mountain.
The dive team did several training runs. The main issue that came up is the need for more weight on their weight belts, so they don't run the risk of accidentally popping up to the surface. It will be especially important at high altitude not to surface too fast. Because the weights they are using were special ordered, it wasn't possible to get more of them in time for the dive. But problems like these don't stop this team for long. Victor simply drove to a nearby town and purchased several sledgehammer heads to use as additional weights.
Nathalie (front), Clay and Rob perform a test dive in the hotel pool.
Left: Randy puts a dive watch on Clay's arm. The divers use coordinated watches to make sure they don't stay underwater for too long. Right: Cristian helps Nathalie adjust the straps on her face mask and breathing unit. The divers all have "squires," assistants who help them prepare for dives and get out of the water safely after diving.
Left: Matthew helps Clay get on his diving gloves. Right: Nathalie and Clay exchange sample bags.
Left: The post-dive procedure is as important for safety as the pre-dive check. Here Cristian checks Nathalie's pulse, while Matthieu checks Nathalie's... Right: Clay (whose new nickname is "sledge") shows off his innovative sledgehammer shoulder weights.
Left: Randy pours some soda lime into Nathalie's scrubber unit, in preparation for a dive. This is the material that reacts with the carbon dioxide exhaled by the divers so that they continue to breathe pure oxygen. Right: Nathalie uses a rubber mallet to tamp down the soda lime. It needs to be well-packed to be effective.
Left: All three divers are ready for a test dive. Eric (front, in red shorts), goes over the pre-dive checklist. Each diver is attached by a length of rope to an inner tube. The inner tubes serve two purposes: the divers can store their gear (cameras, bags of sample bottles) on them; and they tell the people on-shore where the divers are. This latter function is an important safety measure, because rebreathers don't produce bubbles, which typically can be used to track a diver's position in the water. Right: Eric watches intently to make sure everyone okay, while modeling his fashionable fluorescent gloves.
Randy checks Rob's pulse.