Relearning old navigation lessons

Two letters in the latest issue of the excellent Cruising Association magazine* claim it is now safe to rely entirely on electronic charts because backups to the boat’s main chartplotter are so cheaply available. You can leave your old paper charts abandoned in the bottom of a locker somewhere, the argument goes.

However, while researching updates for the yachtmaster book I mentioned last month, I’ve been re-reading intensively about old fashioned navigation techniques I learnt a long time ago, some of which were beginning to fade from memory. It has reinforced for me how important it is to avoid total reliance on electronics and have a portfolio of navigation skills including the old ones.

Traditional chart table at the end of a sail home from Scotland, and the bottle we brought back to celebrate our return .

So I think discussion of electronic charts needs to be a lot more nuanced than some of their more enthusiastic users suggest. Yes, on Spring Fever we have also relied heavily on electronics for many years, but my worry is how easy it is for phone, tablet and laptop software as well as hardware to fail, which can take a long time for the less than totally expert to sort out on passage.

It is certainly true that most well equipped offshore boats will have one or more extra chartplotters loaded on tablets, phones and laptops. Some are backups in case the main plotter system run from the boats batteries fails – that only takes a bust alternator or an engine that refuses to start. I also hear that an increasing number of people are dispensing with dedicated marine chartplotters altogether and relying on tablets etc.

Two examples of what can go wrong: my tablet’s GPS receiver failed last year. After a great deal of googling back home I found out why – I had not updated it for the GPS clock change that took place last year (little noticed, but the navigation equivalent of the millennium bug in 2000). Updated this winter using wifi at home, the GPS started working again, ready for this season. Hands up all those who knew about this and fixed it in advance. My problem was an older tablet. Recent ones would have updated for it automatically.

This was specifically a US GPS problem, and I don’t think it affected the wider GNSS, which includes the Russian, European and Chinese satellites processed by newer receivers than the one in my tablet.

More seriously, my laptop had earlier ground almost to a halt because of some unknown and untraceable software issue picked up I know not where – probably not a virus, or at least not one my Norton protection could find. I abandoned it for navigational backup and planning in favour of the tablet, well before that too showed it could let us down.

This winter, having bought a new laptop, I did a factory reset on the old one, wiping everything except the Windows 7 operating system. Miraculously, it now works like new. So I have loaded the charts, GPS driver and related software again and it is going back on the boat and staying there. I will keep it bug free by not connecting to the internet.

The laptop will be used for planning, with the cockpit chartplotter still our main instrument. But the laptop is old and has a hard disk drive rather than a solid state one, so can mechanically wear out. We may add a further backup in the shape of a small, cheap 7 inch tablet from visitmyharbour.com that’s tough and cockpit proof. (£170 loaded with 2020 raster charts for the UK, France and Atlantic Spain and Portugal).

Computer hotshots might have done fault-finding at sea or in a marina but it took me a whole day at my desk to figure out the laptop solution and sort it, using a high speed internet connection. The software fault had even disabled the DVD drive, which is now working again.

This is not the end of the list of issues. Tablet and phone navigation relies on apps and they do sometimes misbehave. Often the solution is to uninstall and download again – not an option for us at sea. That problem cropped up last year not with a chartplotter app but with one of the best tide prediction apps, though it could easily have been one of the chart apps. This all tells me – a reasonably capable but far from expert user – that the issue of electronics reliability, even with multiple backups, is complicated.

And that is without more basic questions, the first of which, GNSS reliability, I have covered in two previous posts. (On that subject, I have just read a report that GPS spoofing equipment can now be bought for only $100, and how to use it is widely discussed on line).

There is of course the more widely considered question of what happens to your backup tablets, phones and laptops in a knock down, a partial flooding of the saloon, a fire that you may put out but which causes damage or – a nightmare – a lightning strike.

I’ve had a strike on a previous boat, while it was moored on a river – I was ashore – and it destroyed all the electronics and made for a large insurance claim. High voltages nearby can induce large currents in equipment even if it is not wired into the boat’s own circuits. The advice I hear to stick your laptop, tablet and phone in the oven to shield them if lightning is near I find the complete opposite of reassuring!

So we don’t plan to chuck the paper charts, dividers, almanac and ruler in the bottom of a locker somewhere – they’ll always stay ready in the chart table, and we’ll use them from time to time so as not to forget how.

By way of contrast: now reading this 1987 book, which makes even our traditional navigation seem hi-tech. It’s about the last island outposts of Pacific Ocean navigation skills going back thousands of years, which use only knowledge of stars, waves and birds, and no instruments, achieving remarkable accuracy.

* Cruising, Spring issue.

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