ALTEX Arctic Cruise
October 7 - November 7, 2001
Tromso, Norway to the Arctic Circle
Logbook
October 12, 2001: Day #6
In Ice
Mike Pinto writes: The day began for me at 1:00 am when I relieved Amy on the CTD casts. Small chunks of ice were floating by as I as I made my way up to the aft science conning station. We were stationed in a field of pancake ice (small floating layered ice made by first year ice being broken by waves, sliding under other pieces and re-freezing). Both the air temp and surface water temp was -1.3 degrees Celsius (29.6 degrees F). With the assistance of four Coast Guard science technicians, the final two 3000 meter casts were completed by 9:00 am. We continued traveling north as I went back to my berth to catch-up on some sleep.
I awoke just before noon by distant crashing sounds and my bunk vibrating noticeably. I made my way up to the bridge in a light snowfall to see an amazing site. We were traveling through a field of larger pieces of pancake ice and solid areas of ice and we were breaking ice as we proceeded at about 4 knots. The pieces were of various sizes and thickness - some of the thicker pieces appeared to be over a meter (3 feet) thick. The Healy effortlessly made it way by slightly riding up on the ice and breaking it by its own weight. The business end of the Healy's keel is constructed with a solid piece of 15.24 cm (6 inches) cast steel with 14 cm (5 ½ inch) of plate along the sides up to the main deck.
The AUV continued to be checked out for the next set of tests in open water before we go under ice. A problem with the upward looking ice sonar was discovered and fixed. Later that evening a test was conducted with the Phantom ROV to determine how well we can locate the AUV under ice. The ROV was launched in a small opening in the ice and Mark T. piloted the vehicle some distance away from the Healy. We could see the bottom of the ice and what appeared to be krill on the monitors in the science lab. A dive light was dropped over the side to give Mark a target to search for. The light could be seen from about 15 meters from the ROV.
The ship turned its main searchlights towards the ROV and it was discovered that the light could be seen through the ice by the ROV when the ROV shut down its own lights. This will provide an excellent method to lead the ROV on a search grid pattern for the AUV strobe light in the event we lose the AUV under the ice.