The ice holes


27 November 2006

81st day of drift.
 Position: 82?45’N, 136?32’E
 Course and Speed: N, 0.4 knots
 Wind: S, 10 knots
 Sea Ice: Slight movement
 Visibility: Moderate, cloudy sky
 Moon: Not visible
 Air Temperature: -23°C
 Water Temperature: -1,5°C

Everyday we have certain tasks to complete that are essential for the operation of the boat and the maintenance of our scientific instruments.

Often physically challenging and in difficult weather conditions, one of these tasks is maintaining the ice holes. At present we have three holes to keep an eye on, a large one (1m diameter) behind the boat for the large CTD soundings, and two smaller holes located 50 – 60m from Tara. One of these smaller holes is for a fixed depth CTD, the other for an acoustic float which measures the propagation of an acoustic signal from stations a few hundred kilometres away from our location. These instruments are recovered about once a week to recover the data.

 To make the holes in the ice we use specific tools, including a motorised ice drill, chainsaw, ice picks and a large sieve for removing small ice blocks from the water. The most difficult stage is making the hole for the first time, requiring many hours of physical labour for the large hole. After this, day and night we are required to check on the hole and break any ice that has formed. It is not uncommon for 20cm of ice to form overnight when the temperature is around -20?C. Herve, our resident “iceman” explains the difficulty of maintaining the holes, “Any physical activity is restricted by the bulky clothing required to go outside at these temperatures, a large
jacket and thick gloves that limit dexterity. When the temperature is less than -20?C it is difficult to start any motorised tools, plastic and even metal parts become fragile. All of these difficulties turn a simple task into a complex and time consuming operation. One inevitably gets wet hands, and sometimes wet boots during this process, uncomfortable to say the least and at these temperatures potentially dangerous. The scientific material is also sensitive to the cold when out of the water, requiring us to work as quickly as possible. Installation and recovery of instruments rarely goes without a hitch, resulting in more time spent outside. We are always happy to finish the job and return to the warmth inside Tara to take a hot tea or coffee.”