>> GLOBAL POSITIONING SYSTEM

We use a Magellan Nav 6000 GPS (Global Positioning System) to give a latitude and longitude position - or ‘fix’ - at least once a day.

>> PAPER CHARTS

Every 24 hours we mark the latest GPS coordinates (latitude and longitude) on a traditional marine chart to find out our exact location on the ocean. Once out of sight of land, the chart is the only point of reference point to knowing where on earth we are!

This 'position' can then be used to determine the distance and direction we've traveled since the last fix, and what compass heading we want to make in the next 24 hours.

>> ELECTRONIC CHARTS

The Nav 6000 also takes special C-Map cards that store traditional chart information on small chips. As well as saving space, they also enable the GPS component of the unit to marry directly with the charts.

However, due to the likelihood of any electonics failing at sea, they are a compliment, not an alternative, to traditional paper charts.

>> MARINE COMPASS

From the paper chart we work out a compass 'heading', which is the direction we aim for throughout a 24 hour period until the next GPS fix is taken.

210 degrees for example is an approximate heading of SSW (south south west), with 180 degrees being due south.

>> SEXTANT

If the electronics fail we have a sextant as back up. This device was used in the old days before satellites and GPS’s were invented. You can use it to measure the angle of the sun or any other celestial body to the horizon. By referring the date and time of the reading to an almanac it is then possible to calculate your latitude/longitude position. Although a lot more complex than just switching on a GPS, it is still an essential piece of kit to have on board, especially given the frequency with which electronics tend to fail when subjected to a salt-water environment for any length of time.