While transiting south on 10 September, we passed through 20 miles of old and thick first year iceI in what to date has been our closest encounter with ice.  This was not unexpected but, just as the approach to the pack ice edge several days ago clearly showed the difference in value of the various ice charts being received onboard, this transit did the same.  The small scale, low resolution based TOPAZ charts indicated open water.  In contrast, the larger scale and composite nature of the NOAA and NATICE charts using higher resolution but older data clearly indicated ice along our planned route.  It was expected, but we knew it would not likely be as concentrated as the American charts suggested.  As it turned out it wasn’t.  We did not encounter the 6-8/10ths of old ice depicted on those charts.  Though the concentration was never more than 3/10ths overall, most of the ice was multiyear floes some up to 30 metres.  For a lightly ice strengthened ship such as Mirai, that is challenging.  Not at all impassable, but challenging none the less.

Whenever transiting near or in ice, the Ice Navigator is on the bridge providing input to the Captain and his bridge team on tactical manoeuvring based on visual, radar and other sensor information. The Rutter Ice Navigator display combined with the JRC X-band on 3nm range are invaluable, providing appreciation of what is around the next bend as it were.  I explain to the young bridge officers, new to sailing in ice, that the radar makes it look worse than it is, that it appears more concentrated and as we get closer and look out the windows, its not all that bad.  Nodding heads of understanding and sighs of relief result.

Heads up is the key as the conning officer carefully picks his way around the ice.  Not being an icebreaker Mirai avoids any contact with the dense old ice floes, often speeds are dead slow ahead less than 3kts, sometimes even stopped as a floe may be pushed gently aside.  It is slow going, but Captain Tsutsumi knows his ship very well and adroitly manoeuvres through and around the ice, slowly dancing as if to a Strauss waltz.  The Captain and Ice Navigator confer in selecting best tracks through the ice, always in mind the base course that we want to make good, but fully aware that we may have to go way over there to get back to over here.  In fact, when reviewing the course track once we were clear, we ran about 4nm to the east of our intended course line.  Par for the course, pardon the pun/metaphor.  After seven hours and clear of the ice, Mirai again rung up full ahead both engines.

With a light ice class ship the Ice Navigator’s job is mostly about avoiding ice in general.  If you can, go around it, only go through it if you must, and then very carefully.  Operating light skinned ships in any ice is far more of a challenge in many ways than having a heavy purpose build icebreaker under your command.  Its like using finesse versus brute strength to get the job done.  Admittedly, sometimes only brute strength will get you some places, but for RV Mirai, we only go where we can gently waltz, not where we have to break dance.

Capt David (Duke) Snider
Ice Navigator
RV Mirai