Tethered Dives
Ian, Bekah, and Dale will be diving under the ice at Lake Joyce to make scientific observations and measurements. They want to be able to stay down in the lake for as long as possible without getting too cold. One way to stay warmer longer is to wear full face masks with dry suits and other insulating layers. Full face masks keep the cold water off divers faces, unlike regular scuba masks.
Full face masks also let divers breath more naturally, and when they are working hard, they breath more air. However, divers don't have a spare regulator (the thing normal scuba divers breath through), which is a standard safety requirement for diving, so they depend more on the face mask working properly. They don't always work perfectly. Thus, the divers are tethered to the surface so someone at the top can pull them up if something goes wrong with the equipment and the diver needs help. This is also a very good idea when diving under the ice; it ensures that the diver can find the dive hole even if they get disoriented. Since the divers are tethered, it is easy to supply their air from the surface as well, so they don't have to carry air tanks. They just carry a small emergency bottle of air (yellow bottle in the photos below). Also, communications are added so the person on top knows if something has gone wrong and the diver can entertain the tenders watching their air supply with song or important scientific notes. The air supply and communications are controlled by a box attached to four air tanks. The control box also has simple pneumatic pressure guage to accurately determine dive depth.
Ian, Bekah, and Dale did their checkout dives on this equipment yesterday. We all went out to a cherry/melon/apple/tomato on the ice that was positioned over a dive hole.
The divers went down one at a time with the full face mask and the yellow tether.
Dale saw a giant jelly fish and wished he'd brought down his camera. I played with my Nikon camera for the first time down here and found some interesting subjects in the dive locker.
Full face masks also let divers breath more naturally, and when they are working hard, they breath more air. However, divers don't have a spare regulator (the thing normal scuba divers breath through), which is a standard safety requirement for diving, so they depend more on the face mask working properly. They don't always work perfectly. Thus, the divers are tethered to the surface so someone at the top can pull them up if something goes wrong with the equipment and the diver needs help. This is also a very good idea when diving under the ice; it ensures that the diver can find the dive hole even if they get disoriented. Since the divers are tethered, it is easy to supply their air from the surface as well, so they don't have to carry air tanks. They just carry a small emergency bottle of air (yellow bottle in the photos below). Also, communications are added so the person on top knows if something has gone wrong and the diver can entertain the tenders watching their air supply with song or important scientific notes. The air supply and communications are controlled by a box attached to four air tanks. The control box also has simple pneumatic pressure guage to accurately determine dive depth.
Ian, Bekah, and Dale did their checkout dives on this equipment yesterday. We all went out to a cherry/melon/apple/tomato on the ice that was positioned over a dive hole.
Rob explaining the face mask to Bekah
Putting on Ian's mask
Bekah ready to go in
This was Bekah's first time, and she found the face mask heavy and awkward. However, she did manage to salvage a carabiner and weight bag off the bottom.
Dale ready to put his mask on
Regulators
Work Space
The dive trip was a nice break from the lists and packing again. Afterward, we got almost all of the rest of our gear packed, weighed and labeled. Today we took it down to the helicopter pad. It was two pick-up truck loads, and we'll still have some more things later this week, including microscopes and chemicals. The work is getting done, but more and more seems to come up. Eventually, we'll fly away into the field and have different work to do. I can hardly wait!
