Will Oxley - navigator aboard Doha 2006 - with thoughts on icebergs, and how to avoid them
Iceberg A word that causes great concern for sailors, race committees, rescue authorities and, above all, family and friends following these southern ocean races. Many races have imposed restrictions on how far south boats can go by placing virtual buoys or lines on the ocean that yachts must come above. There is plenty of debate about this but to my mind these waypoints can create major headaches for navigators and actually reduce the ability of yachts to avoid bad weather which increases the risk of problems.
Thankfully the Oryx Quest Race committee put the onus on the yachts in this race to navigate with prudence. Our only waypoint is Antarctica to starboard! As I sit here on hopefully my last night of radar ice watch for this race it is worth revealing the ‘good ice data’ I mentioned in an earlier email. Traditionally avoiding ice in the southern ocean has been a matter of a good lookout, a good radar watch, watching the water temperature and a ‘bit of luck’. However, things are much more sophisticated in the northern hemisphere ice areas, mostly I guess, due to the prevalence of shipping in these areas. The Canadians are the world experts in this area.
One company in particular, C-CORE, operating as part of a consortium called the Northern View, supplies a portfolio of information products and operational services based on Earth Observation data, including an operational iceberg-tracking service for shipping and offshore operations in Canadian waters. The service uses data from the European Space Agency’s Envisat and the Canadian Space Agency’s Radarsat satellites. Why am I telling you all this when we are a long way from Canadian waters? Well, during the Vendee Globe C-CORE extended their activates into the waters of the southern hemisphere. They acquired images ahead of the race route, using the Synthetic Aperture Radar (SAR) instruments on Envisat and Radarsat and reported the positions of any observed ice to the competitors in the race.
This was a huge step forward for racing in the southern ocean. The Volvo Ocean Race has been discussing using the technology for their race this year and introduced it to the potential skippers and navigators at a briefing in the UK last year. As soon as I knew I had the nav position in this race I got onto this. We contacted C-CORE to seek their assistance for our race. As a competitive soul I was pleased to find out that our opposition had not been in contact with C-CORE.
So how does it work? Desmond Power of C-CORE states that “Icebergs typically have a stronger radar signal return than the open ocean. After initial processing to get rid of ‘cluttering’ effects from ocean waves we analyse the shape, number of pixels and intensity of signal returns to differentiate between icebergs and ships, which can appear similar. Sometimes we are uncertain so rather than hold any potentially useful information back we label the returns according to a confidence classification ranging from strong to weak certainty.”
A C-CORE press release states that “C-CORE has been using Envisat’s Advanced Synthetic Aperture Radar (ASAR) in Wide Swath Mode (WSM) giving 400 km swath to a resolution of 150 metres, together with Radarsat ScanSAR Narrow Mode with a 300 km swath to a resolution of 50 metres.” We chose the wide swath mode giving us good confidence of spotting any ice 150m or greater in size wherever they could map for us. We got them to target the areas where the ice was known to be bad.
We began receiving the information from the 17 February on board and have had at least one scan a day through to the 25 February. It did not give us full coverage but has been a huge tactical (and psychological) advantage to planning our track through the southern ocean. Of course we have had the moral dilemma of whether or not to share our information with our competitors.
Brian and I discussed it before the start and we agreed that we would provide it in the event that a competitor looked like they were putting themselves into a dangerous situation with respect to ice. Providing the data later would hopefully keep them safe but remove the tactical advantage we had gained from having the data for longer. Our moral dilemma came to a head two nights ago when our plots of the competition showed that Cheyenne was about to sail into one of the known ice field areas. We had a quick chat then rang Cheyenne and arranged to send them the data by e-mail. Of course we felt we then had to give them all the data and also provide it to the others. It was an easy call in the circumstances with a comfortable lead and we like to think we would have been just as prompt even if we were neck and neck. I had to smile as I imagined Wouter at the nav table on Cheyenne suddenly receiving at least 100 ice targets to plot. It would have freaked me out!
As they say ignorance is bliss in ice territory in many cases. We have been very cautious with the knowledge of just how much ice is around and just how far north it is. Much of the ice is actually north of our course and so an ice waypoint to keep us north would have actually put us in more danger, so full credit to the race committee. The overall picture to the horn from here now seems clear of ice so we just have to worry about avoiding any upwind work in the southern ocean. Not a pleasant thought in any craft (and I should know!) let alone a maxi multihull!
Cheers for now.