What would you do next? Tech failure onboard

You’re sailing offshore, out of sight of land, when your boat’s main high-tech electronic navigation tools suffer equipment failure for an unknown reason. You can’t fix them, but you do have paper charts onboard.

A sailing yacht in a moderate sea

Photo: RNLI/Nathan Williams

Do you?

a) Send a DSC alert (digital selective calling) from your ship's radio followed by a Pan Pan voice call on Channel 16?

b) Turn directly towards the shore and drive until land becomes visible?

c) Fix your position using an alternative means?
RNLI Lifeboat Crew Trainer Adrian Bannister

Photo: RNLI/Mark Scott

RNLI Trainer Adrian Bannister

Expert answer

Adrian Bannister, RNLI Lifeboat Trainer

Fix your position using an alternative means (C). You can check your proximity to any navigational hazards on the chart, like shipping lanes, wind farms and shallow waters. You can then decide if you continue, turn around, or head to the nearest port.

The method of fixing your position might differ depending on whether it’s day or night.

Ideally, you’d always carry a portable GPS or GPS-enabled mobile device.

If you have one, use that first.

If not, and it’s daytime, use your ship’s log, or previous fixes on your chart, to work out your last-known position. From that, apply dead reckoning, factoring in tides and tide streams, plus nearby physical features like buoys, to estimate your current location.

At night, without a backup GPS, yachtmasters can also use rising and dipping distances in conjunction with an Almanac, to calculate the boat’s distance from a light on the horizon.

How to calculate dipping distance
How to calculate dipping distance

Every vessel should have a chart onboard for the appropriate area.

Pack plotting equipment including a Portland plotter, parallel rule, or a rib plot, plus something to measure distance, like a pair of dividers. And a 2b pencil (plus sharpener).

Always navigate with extreme caution. Even when boating out of sight of land there can still be the risk of grounding, so ensure you have sufficient depth of water by checking charted depths and watching the echo sounder.

Get more RNLI advice on yacht sailing and motorboating here.