Electronic charting systems are a step up from the olden days of pencil, dividers, and paper. Used correctly, they reduce workload and offer a higher factor of safety, especially in difficult conditions. However, there are numerous risk factors associated with using electronic charts, so we feel it is wise to maintain a healthy dose of skepticism and double-check the results.

In this case we are using Nobeltec software, and because we do not have Canadian NDI electronic charts (which we’ll acquire before we come back) we are using the Nobeltec “Passport ” (vector) charts.

One of the problems with all electronic charts, as opposed to paper, is that at smaller scales (covering more area) it is easy to miss important details. This seems to us to be less a problem with raster scans of official charts. It is much easier to lay out a series of waypoints to the next destination at small scale. However, unless you go back and check at larger, more detailed scales, one risks missing important detail.

Coming down the Queen Charlotte Straights, outside of mainland British Columbia, there are lots of shallow patches, reefs, and isolated rocks. We’ve got detailed paper charts on board, so these navigational hazards are easy to pick out.

We were running before a freshening northwesterly breeze, enjoying the occasional surfs as the seas built and stacked up with an opposing current. The following radar and chart images are set up for heads-up viewing, so the top of both chart and radar images indicate what is ahead (we are actually going south).

The Furuno 2117 radar is set on 12-mile range, its primary use at this point being to look out for cruise ships and other traffic, and to check distance off various landmarks. If you look a little to starboard of our course out 5 miles you will notice a strong target. The radar is set on 12-mile range so each ring represents 2 miles. We began to notice this target at 7 miles. The speeds shown in the upper right-hand corner are from continuous surfing – ideal conditions for having fun!

Here is a crop, giving you a better view of the target.

Next we want to show you a screen shot of the vector chart on one of the scales we were viewing. If you look ahead and to starboard, there is no indication of a rock or obstruction.

Going up a notch in scale (covering less area in more detail) we see a simple black + to indicate this obstruction. No information on what this is – reef, rock, island – or its height.

When we are in this type of navigational situation we usually have the charting computer set up so we can see three chart scales. In this case, on the left is a medium scale, in the middle is detail close in to the boat, and to the right is a small scale to give us a feel for the overall situation.

And that + on the vector chart? A major rock, easily viewed (in good weather) with binoculars at 4 miles. This was a good reminder to us: check paper charts for risk factors, keep a sharp lookout ahead, make sure the radar is well tuned and working correctly, and never put full trust in any single source of data, especially electronic charts.