This picture shows where we anchored our boat on the weekend. Do you notice something odd? Our boat was apparently on land. It’s not because we ran aground. We were indeed afloat. It’s because the maps are wrong.
The coastline of Greenland is probably one of the worst mapped coastlines in the world. The Danish Geodata Agency requires all commercial ships, or ships over a certain size, to use their offical navigational maps. But in practice, noone in their right mind would rely on them. For example, the official route coming into the port of Kulusuk – one of the main settlements in east Greenland – goes through the middle of an island. A colleague in Denmark on an expedition to east Greenland found that the GPS positions of places she had visited plotted hundreds of metres out to sea. She asked me for a more accurate map she could use. But there is none. In North Greenland, in particular, there are areas where the coastline is out by as much as three kilometres. And when it comes to bathymetry, even in well trafficked routes water depths are very poorly known, or more often completely unknown. As soon as you sail into most fjords those handy little depth numbers disappear and one is left creeping slowly across an alarmingly blank map, hoping to avoid rocks by watching the depth-sounder or simply looking over the side of the boat.
The Danish Geodata Agency is of course aware that their maps leave something to be desired. But their official line is that, even though they could make corrections, they choose not to. The reason? They are not in a position to comprehensively correct their maps for all of Greenland. So they prefer not to correct any, so as not to give the impression that their maps are reliable.
So how do ships operating in Greenland deal with this? Instead of using the official maps, many use Google Maps, provided through iSailor – software designed for sea-based navigation. Google Maps tends to be much more, if not completely, accurate. Or sailors can also more-or-less avoid using maps entirely by using existing tracks. Commercial ships typically travel the same route over and over, so can simply follow their previous GPS tracks, removing the necessity for accurate maps. Amongst local fishermen and leisure sailors, GPS units with years of tracks are prized assets, sold at a premium. And track files themselves are also sold and traded.
Fortunately, progress is being made. There will soon be a publically available high-resolution digital elevation model for Greenland – the basic data required to make topographic and coastline maps. This means that, in the foreseeable future, there might be reasonably accurate coastline maps for Greenland. As for bathymetry maps for navigating coastal waters – don’t hold your breath.
