The Offshore Voyaging Reference Site

Backup Systems

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In the last chapter I looked at whether or not it was safe and seamanlike for us offshore sailors to completely dispense with paper charts for our primary navigation system, and I concluded that it was.

Now I’m going to look at the thorny issue of backup and redundancy and more specifically backup without paper charts. Is that even possible, or must we continue to carry at least some paper charts in case the electronics bite the big one?

And if it is possible to dispense with paper completely, what combination of electronic gear and electronic charts would constitute a proper and seamanlike backup?


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David e Bell

A thought (based on long experience with must run computer systems) for a dual iPad (or other computer) system. If your backup is an iPad I would have two identical iPads and one would always be in the Faraday Cage as suggested above. And that is not enough. As a matter of course you should swap the iPads on a regular basis. “If it’s Monday then swap iPads” or the like.

I remember a data center where the backup failed every test, until they started using it every day. If you depend on something regularly it is much easier to remember it’s care, feeding, and updates.

That being said, my new boat is getting a large chart table (in addition to the table in the salon) and a flat chart storage within arms reach.
D

Peter Morley

My primary system is a combination of GPS, paper chart and logbook, so the backup for the GPS is eyeballs/hand-bearing compass/dead reckoning/lead-line/sextant as appropriate (assuming that depth sounder and fluxgate compass may well be inoperable if the GPS is).
The paper charts stay on the chart table so are at minimal risk though I may well have the pilot book in the cockpit with me.
I agree with David about the desirability of the back-up system being used – the same applies to paper charts when considering John’s points about the accessibility of the chart (which is a strong argument for a separate chart table so the local one can always be out) and practice with more traditional navigation.
I would be interested in trying a tablet system at some point but I must confess I’m wary of touch-screen systems. Calabria’s point about system redundancy is interesting.

Calabria DiMarzio

The 800 pound gorilla has been on a diet lately. The iPad (3rd gen and later) receives both GPS and GLONASS, so the shutdown of either one will not impair its ability to act as your backup SATNAV.

http://en.wikipedia.org/wiki/GLONASS#Receivers

Jeffrey Siegel

Great to see experienced cruisers stepping up and giving a balanced view of paper charts and where they fit in 2014.

A couple if things I’ve learned along the way…

– A smartphone capable of being a backup chartplotter is a fantastic lightning/general backup. While we use our oven for larger devices (and I’m not completely convinced of the risk with that and I have not seen evidence of any failures from people directly affected), I like keeping my phone in my pocket during a storm. I think my own body acts to protect the device in my pocket – and if there were enough ambient charge to destroy an electrically shielded phone, I’d probably die from cardiac arrest through the same charge. Also, in the ultimate outcome of launching a life raft, I like the idea of having the phone in my pocket to give me communications and charting/calculations, etc. Obviously, the communications aspect is only useful for near coastal cruising.

– If the GPS satellite constellation went down, there is another one run by another government (GLONAS). Many GPS devices dupport both constellations – it’s good to have that. If both of them go down, Earth is likely in trouble or there is a significant threat happening worldwide.

– A big “a ha” moment came to me when I realized that you can easily do DR plotting on an electronic screen in multiple ways if GPS ever does fail. There are even apps today that allow you to enter your course and speed and it’ll plot your track with every-second updates.

– People often think that an iPad or phone has only a 10 hour or less battery life. GPS use brings that down a fair amount. But if you’re in a backup mode, you certainly don’t need the screen constantly on. You can turn it on, get your fix, feel good about your track or change course, and turn the device off. Working with it like that, the battery life will be significantly extended.

– There are a few pull-string magneto battery chargers on the market. They have more use than solar for the obvious times when you’re in a backup situation because of a storm. I think they should reside in a direct bag. It’s been hard for those charger companies to stay in business because it’s not a general need but the chargers exist.

We physically removed all paper charts about 3 years ago. That said, if we were crossing an ocean, I’d want some large scale (low detail) ocean charts if we were going more than a couple of hundred miles offshore.

Matt

You can thank Harlan Carswell for actually testing the RF shielding on a whole bunch of microwaves and finding them generally inadequate as Faraday cages…. I am used to big heavy metal ones, but after having a closer look at some modern microwaves, it seems that there’s usually no electrical contact between the door and the box around most of its perimeter. So no Faraday cage effect.

I’m going to stick with a grounded, fully conductive cage, i.e. a copper or aluminum box, as the recommended protection for the backup backup gadgets. But you can’t run charging cables into it (that would kind of defeat the purpose), so you have to remember to take the things out and check them every few days. Better than getting lost, I guess.

Simon Wirth

Hello Matt
Have you ever taken a look into EMP-protection devices to get power into the box?
As I see it, this could be a valid way to get power into the cage. Maybe even to get data signals in, as there are protectors for every kind of signal. Do you think this could be a valid option?
Regards, Simon

Alan Tyson-Carter

I had a complete engine and electric failure 4 days out of Gibraltar. I had already put into Malta and Sardinia to try and fix the engine, but when it failed again, though I could see the Spanish coast, I decided to sail on to GIB the Columbus way. They at least spoke English there! I always kept the relevant chart on the chart table below and plotted my positions by hand every hour even when I had power and all systems. Yes I had a hand held GPS with sufficient spare batteries and preprogrammed with way-points for the relevant passage I was making, but preferred the sextant, hand held compass and dead reckoning to get me there. By training I’m a staff officer and so have always worked on the assumption that what can go wrong will go wrong, which is why I would never, ever sail without paper charts, a hand held compass and sextant etc. I had also connected all my ships radios directly to the ships batteries so even though I had no navigation devices or engine, when push came to shove I could radio for assistance. This was the case too when I had an electrical fire in the Indian Ocean and lost all systems because I had to turn the main battery switch to off!

Brian Lockett

On a run from Newport to Bermuda several years ago on a Swan 53, we were 60 nm NE of the island at 2300 hours, expecting to enter at St. Georges. NE wind in the 30s, state-of-the-art Raymarine chartplotters. Three of them. And they packed up. Glad to have those paper charts and a hand-held GPS.