How are diving holes mantained?
We're currently in the winter to summer transition and temperatures can vary between very cold to somewhat nice. One of the ways low temperatures affect our research is by causing the water in the diving hole to start freezing and slowly closing the diving holes that were made for our divers to the point that the hole becomes very small for a diver to pass through it. That's when our team has to go in a "Let's melt a hole" mission. This time it was Paola, Alex, and I who were trusted with this very important quest at the Pearse site.
It had been a few days since our team had last visited this site. Shortly after 9am, we drove a Pisten Bully into the unknown, not knowing how small or different this diving hole would be from the last time our crew had visited it. Once we were on the sea ice, we fought against the wind to get our tools into the dive hut. It was pretty cold and windy; we were wearing all our layers and you could still feel the wind hit you every time you were outside.
After bringing all our tools inside, Alex started setting up the big star of the day. The star is called Hotsy, a pressure washer that has been repurposed for warming up glycol in the field. The cold was surrounding us and Hotsy was taking a while to start but Alex was persistent and finally got to it work after several minutes. Then, it was game time. We put a hose down the dive hole to collect seawater and then the warming of the glycol warms up the water as it is being collected from the ocean. We then took turns using the hot water to "carve" into the ice that was covering the hole and break it. The sea ice can get really thick so we had to use a really long pipe as a hose to get through the whole thickness of the sea ice. Around this time the thickness of the sea ice varies a little depending on where you are. Around our Pearse and Jetty sites, which are right in front of McMurdo, the sea ice is about ~2-2.5 meters thick. In Cinder Cones, which is a little bit farther, the thickness of the sea ice is around 3 meters.
It was great team work. We accomplished to get the dive hole fully open again after a couple of hours and then it was ready to go for our team to dive again.
I discovered there is something very calming about the melting of an ice hole. You stand there watching as the hot water slowly melts the ice and see the ice pieces float to the surface as they get broken. I think I might have found a new calling; if you need someone to melt a hole in the ice, you know where to find me.
Wow, three meters of ice! How thick does the ice get at the diving hole between visits?