Judging distances at sea

Being able to accurately judge distance at sea is just as vital in the digital age as it ever was, says James Stevens

- James Stevens

The universal use of GPS has made navigation simpler and improved safety at sea. Coupled with this revolution has been a fading of traditional navigation skills and observations. When electronic navigation was widely introduced in the 1990s the RYA was very concerned about the potential abandonment of these navigation techniques, which are a backbone of the yachtmaster syllabus. This was mainly because of a lack of trust in a system which relies on signals from satellites 12,500 km away.

GPS proved to be much more reliable than we all feared, so only a minority of skippers get a pencil out to navigate these days. However, there are some skills which are still relevant and helpful for judging position and distances at sea, even if they simply ensure the navigator is on deck rather than staring at a screen below. This visual watch is important to avoid hazards which are not on the screen, such as other small craft and lobster pot floats.

It is also a fact that as sailors, we are navigating boats in the real world with physical hazards, not the virtual world. While it’s tempting to follow the boat icon across the chartplotter, it’s vital to remember that this is just a source of navigational information (albeit a very good one) to keep us safe in the real world. Being able to translate what we see on screen to the marks, features and hazards around is a critical skill. Conversely, being able to judge distances helps us corroborate what we are seeing with what is on the chart, whether it’s electronic or on paper.

As an example, competitors in the Round the Island Race will know that there is a wreck, the