What happens when the screens go dark? Although this seems pretty unlikely in today’s world of über-connectivity, with Iridium and Starlink on board many boats and every device seemingly having an inbuilt GPS, what if a lightning strike or corrupted software update suddenly puts all your navigation systems out of action, or the boat’s charging systems and batteries are incapacitated?

It might be a rare occurrence – but it’s not impossible. You might need to sail in ‘dark’ mode for a time while you reboot or rewire your nav suite. Or you might decide that other repairs have to take priority, and that complex electronics are best fixed ashore.

After recently completing two circumnavigations – one solo – using only the navigational equipment that was available in the 1970s (while competing in the Golden Globe Race and Ocean Globe Race), I’ve now become familiar and quite comfortable sailing without modern electronics, so the following are some essential points on what to do in the event of a total systems failure:

Make regular position entries into your log

1 Keep a log

Good log keeping is a fundamental part of any back-up plan in the event of a total loss of navigation systems. In the age of the chartplotter, it’s easy to get out of the habit, but it’s just good seamanship.

I’d suggest that a log update every three hours is the minimum for offshore sailing and every hour for coastal sailing in unfamiliar waters. That includes plotting your GPS position on a paper chart or at least entering in the boat’s log book.

Your log book can be as comprehensive as you like, but should always include the GPS lat/long coordinates, course steered, average speed and/or distance logged through the water.

Notes on barometric pressure, sea state, cloud cover, sea temperature etc are also all useful to help you build a picture of what’s happening around you.

This way, if the lights do go out, your recorded position is no more than three hours old: if you’re cruising at 6 knots that means it’s only 18 miles out. In fact, if your log includes the boat’s course and speed for the previous three hours a quick dead reckoning will give you a starting position that’s probably accurate to within a few miles.

The humble paper chart and dividers. Photo: Zoonar GmbH/Alamy

2 Paper charts

Like good log keeping, paper charts are a fundamental part of any back-up plan, be that inshore or offshore. As a minimum, have the ocean planning charts for the area you’ll be sailing through and then larger scale charts for any coasts where you plan to make a landfall, and ideally for any areas you’ll sail past that may become ports of refuge.

3 Pilot books

A great resource to have on board, pilot books are not only filled with useful information about the places you are sailing to (or in my case, sailing past!), but if your digital charts go blank they provide invaluable harbour diagrams, tidal information, and mini chartlets that may be just enough to get you into a port or anchorage safely.

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4 Hand-bearing compass

This most humble piece of kit, a hand-bearing compass is something every boat will probably have tucked into a locker somewhere.

It’s a critical bit of equipment for coastal navigation, a back up for the ship’s compass. Use it for collision avoidance (remember your AIS may be down too) and if you start taking star sights you’ll use it to identify the correct navigational star in the sky. Hang it back up in pride of place at the nav table!

Hand-bearing compass in action. Photo: Paul Gibbins Photography

5 Dead Reckoning (DR)

The art of estimating your position at sea, based on course steered and speed or distance travelled, DR is your basic building block of fixing your position and ultimately navigating to a port of refuge. It’s also the first step in celestial navigation.

All you need for this is good log keeping, a compass, a speed log and a ship’s clock, ideally backed up with an accurate digital watch.

The first thing is to mark your last known position on a paper chart or a plotting sheet. A basic DR takes your compass course steered, converted to True (don’t forget variation, in UK we tend to ignore variation, but if you’re off the north coast of New Zealand and heading for Tahiti then it’s going to be 20°-plus that needs to be taken into account) your average speed and the time elapsed since the last fix. Draw this out on the chart and you have a DR fix.

If you have tide or ocean current information from your paper charts, almanacs or pilot books, then combine this with an allowance for leeway and you’re getting close to a more accurate estimated position or EP.

Photo: Pasi Nuutinen/PPL/OGR

6 Celestial navigation

I’m biased, but this is the ultimate mechanical back-up to get you on track. The first thing to be said is you’re not about to become a sextant expert overnight: a good star sight with three or more stars would give you an immediate fix, but that’s not an easy task. Both identifying the stars and taking an accurate sight at twilight are going to be difficult without practice.

However, everyone can identify the sun so start with a series of sun sights during the day – what is known as a Sun, Run, Sun, which, combined with your DR, will start to give a pretty accurate idea of your position.

Having a sextant and little knowledge of how to use it won’t give you an immediate fix, you’ll build up your first fix over the course of a day, with a morning sight, a noon sight for latitude and afternoon sight being the minimum needed. Then over the subsequent days this can be refined with more sights along with careful tracking of your DR in between.

Essentials for old school navigation. Photo: David Pugh

7 Communications

If you’re lucky enough that your VHF is still working, then speak to any vessels that you spot, or that you hear over the VHF. If you can get a merchant vessel to respond they’ll happily give you your GPS position, some indication of weather conditions ahead, and will normally be willing to relay your position and condition to a shore station by email.

HF radio is another great tool to have on board as part of your back-up plan. What most people now consider a piece of retro equipment can, with a little prior preparation before departure, provide you with a vital communications link when other systems fail.

Before you leave make sure you have lists of times and frequencies for marine weather WHO broadcasts in your sailing regions. These can be found in the weighty Admiralty publications, but equally can be found online and printed off before departure.

Radio nearby shipping to confirm your position. Photo: James Mitchell/WCC

If you’re sailing in a rally or in company then setting up a daily ‘buddy call’ over HF not only allows you to chat without using your data plan, but also gives you a way to share weather conditions and communicate any developing issues that you might have with the other sailors who are likely to be your nearest point of support in the case of an issue at sea.

If your sat comms go down they can alert other vessels or shore parties that you have an issue, and on your plans and ETA etc.

Look for HF radio passage monitoring services, such as the amazing Passage Guardian Radio, a free service provided by the dedicated Peter Mott from New Zealand. If you file a float plan before you leave, Passage Guardian will track your voyage, monitor weather that might impact you and most importantly give you a schedule for a daily HF radio call. On these calls you can log your intentions, receive weather updates and – in the case of an issue like the loss of nav systems – share your situation with family and team ashore.

Remember to be your own backup

Although the idea of losing your GPS, chartplotter and shiny new sat comms system during a major ocean crossing might fill you with anxiety – and have you buying GPS-enabled back-ups to back-ups – with a little confidence in the skills you already have, and a few that can be easily learned, you can relax more in the knowledge that you are your own back-up plan. When you make landfall using traditional navigation you may just find it to have been one of the most satisfying sailing achievements of your life.

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