The Offshore Voyaging Reference Site

Backup Systems


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.

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.

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.


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.


Hi, we go cruising in a 15 foot long open sailing boat so our requirements are probably a bit different to those of most people here. Back in the ’80s I went over to France and/or the channel islands for a summer holiday for several years in a row and this required a single handed passage of 40 to 8o miles each way. I only had paper charts in those days and they were of limited use in an open boat – the true paper ones quickly became soggy, the plastic ‘paper’ ones from Stanfords were better but even those were hard to use because I had to sit out on the edge of the boat much of the time and there was no where to lay out a chart. Once clear of land, most of my navigation in those days was a matter of heading south by compass to find France (from the UK) then north by compass to find the UK from France. It worked every time, I never had a problem, I may have been a bit lucky.

In more recent times most of my sailing has been coastal cruising with Josephine but we have made occasional passages out of sight of land. Our first hand held GPS was one of the early models which did not include any mapping, but waypoints could be stored and it would give you a position relative to nearby waypoints and that alone made paper or plastic charts pretty well redundant for our purposes. Then a few years ago along came smartphones with waterproof cases and navigation Apps. In a way that rather spoiled the fun by making it all too easy. However, I have to agree with others here that the small screen size of a smart phone is not ideal and with the system we had much of the text on the chart app was too small to read with sun tired eyes. However, if its too wet and windy to use a paper chart then even a small screen is a lot better than no screen. Then a year or so ago we moved forward to an Apple Ipad in a waterproof case. That would pretty well take care of all navigation for our purposes except for one defect that no one here seems to have mentioned. Even though the IPad in a suitable case is waterproof, you cant actually use it when the screen is wet – salt spray on the touch screen has the same effect as fingers randomly crawling around on the screen. (same is true of a smart phone of course) We find that whenever we are sailing to windward with spray coming on board we have to struggle to hold the IPad in the shelter under the foredeck while sitting on the side deck and even then we have to keep drying the screen with something like toilet roll – when all the toilet roll is wet that’s just too bad, no more navigating! It really would be nice to have a device with the versatility of an IPad or small computer but which could be operated with waterproof buttons rather than a touch screen.


Great Article.

We have gone the ipad for backup. I must confess the ipad is also the onboard entertainment device though, we had great intentions of purchasing a second unit but haven’t yet and there is definitely every chance of Peppa Pig running the battery flat at the worst possible moment, thankyou for the reminder!
We do really like having paper charts as well, not so much as the backup, but as a supplement to the gadgets. I find the paper charts are far better for passage planning, and often give a better perspective than ‘vector’ based chartplotters particularly to the more inexperienced navigators like us.
There is just something about paper that makes things clear and makes me feel comfortable with my decision making, that might be pure irrationality but there you go.


Hi John
If you carry a Sextant it might be worthwhile to download and print out the relevant daily pages for your planed passage. This would give you longitude in case of an emergency for the price of some sheets of paper.
I found it difficult to find the nautical almanac on the internet so I made my own one which can be downloaded here:
Let me know what you think.


Hi John
I did some in depth studies to determine if there was a watertight box to iPad’s that also included a watertight power supply. (IP 68). Also, the box must come with a mounting system, suitable to be mounted at the helm station, under the spray-hood or at the chart table.
To my surprise I discovered that only one supplier could fulfill all these requirements.
As a further comment to using an iPad as a backup, one must also consider how to charge it in case of a total power loss. I believe a hand held GPS together with a pile of extra batteries cope with that situation.

Best regards


Hi, John

As usual, great job.

As you built the opening scenario, I chose tack right away, tack, tack! I’ll take my chances with the ship. I’m certain of what damages the rocks will do. That was fun and read like a re-account. There’re a few great shares here. I’m in the middle of the lightning link, good stuff. I feel the same as you regarding paper, I started there, it’s natural for me. You wrote “be better about practicing our traditional skills”. I’m reflecting on teaching Kathy DR, it’s a lesson not practice. Although, it’s in me, I never practice. I just don’t. I just trust in my skills. I think what suffers is my comfort level and I think that’s a big deal. In the opening scenario, we should be comfortable and calm with it. We manage a lot of systems out there. Our mind is one too. If practice keeps my comfort in check, I’m all about it. Next month, I’m taking Halcyon Charleston to Maine. As you mentioned “practice”, I thought I should run it DR and only use alarms. I feel conflicted or maybe lazy is the more the truth. I shouldn’t feel challenged but I do. I’m bothered that a big part of me just doesn’t want to do it. I guess I’m also weighing in on paper vs. electronic. I have to keep paper alive. I think it’s critical. Thanks for that consideration. My fist Google from this article will be “Bubble” ?

Bill Attwood

All great stuff. I carry and use the full astro gear – with paper charts. Using the heavens to find my position will never lose its magic, although I have been known to use unseemly language when conditions are difficult. AND, I always check my position with the GPS. No plotter, but an Eee-pc with OpenCN charts, to use in an emergency for a harbour where we have no large scale chart or harbour plan. The charts are mostly from Bellingham, copies at approx 2/3 size. Their chart folios are a real bargain. The almanac costs less than $25 so I see no reason for not buying it each year. The other tables have a longer lifespan. I have downloaded Enno´s almanacs to check this year against the official version and am really impressed at his freeware.
I have used chart plotters on other boats, but don´t feel comfortable with them, and the discipline of pilotage with a paper chart seems to me to be a safer system than relying on the boat icon displayed “clear of all dangers”. Please don´t take my comments as criticism of seamen who do use electronic charts and plotters, they´re just not my thing.
Yours aye,

richard dykiel

FWIW I’m sailing a Dana 24 and space is at a premium; mostly coastal but planning on doing offshore passages in the next years. Currently I’m using an ipad mini, running iNav/X and vector charts, with a lifeproof case for protection. I have paper charts for my nav area, and wouldn’t consider going on the water without them nor a hand bearing compass: I do my passage planning and plotting on paper, and use the ipad for ‘situational awareness’ when close to shore. The ipad is secured under the dodger with a RAM mount.
I learned celestial last year and carry a sextant. I made it a point that my celestial plotting would be an entirely pen and paper exercise, given that I intend to have it as GPS backup. The nautical almanac has NAO sight reduction tables which I find handy to use.

Dave DeWolfe

I may be old school — but I firmly believe that having paper charts and the skills to use them is an essential ingredient of good seamanship. I’ve been using them since 1965, when I started me seagoing career as a hydrographer. I also use chart plotters and an iPad. But my backup plan is always paper charts, which I keep up-to-date via Notices to Mariners.

I own and operate an RYA Training Centre in Nova Scotia. For our higher level training we INSIST that people learn to be comfortable in navigating into an unfamiliar port, at night, with no electronics. Why? Because some day you may have to. Why not develop the skills and keep them sharp? It’s not that expensive, and I believe it makes you a more professional sailor. I chuckle when I hear a cruiser refusing to buy paper charts because of the cost yet will put substantial resources into something like a spare iPad or laptop.

Official charts (paper and electronic) are a best effort to display accurately what is around you. Third party charts (e.g.Navionics, C-Map) are copies and are not better. In fact, the reformatting that they do can introduce errors, such as completely missing a small islet just off the Nova Scotia coast.

I get teased sometimes and get called the ‘ancient mariner’ because I do traditional navigation and use paper charts. But I don’t fret about what may happen after my electronics get knocked out by whatever reason. I have the charts and the skills. To me it is satisfying.

On a final note, I am an RYA/MCA Yachtmaster Examiner for both Offshore and Ocean. I teach and examine these skills. I think they are hugely important. And it is sure interesting sometimes, when I am conducting a Yachtmaster Offshore exam at night, to see what the candidate does when I deliberately put my hand over the GPS receiver on the pushpit.


Ray Verlage

Do you have IPAD mounting photos on your dodger?
Ray V

richard dykiel

Unfortunately no, and boat is on the hard under tarp. I can take pics of the mount sometime this week if you want.

Victor Raymond

Hello John,
Two years ago, about 4 hours SE of Bonaire we were caught in a squall at in the early morning that disabled all GPS systems on board. We were navigating by iPad at the time. We started up another iPad, iPhone as well as other spare GPS receivers. Nothing, no GPS signal. Judy panicked but I said we would just continue on the previous heading until landfall. Even without GPS the iPad will display the charts just fine. Within an hour all signals restored by themselves and all was well.
Recently we picked up an inexpensive Lowrance chartplotter with charts of all North and South America on a tiny chip. Chips are available for the rest of the world.
It makes a great backup.

Simon Wirth

Hello Victor
This seems to happen more often than we think. I had the “fortune” to get a similare experience last Sommer while sailing the Swedish coast newar Stockholm. Two completly seperate GPS plotters took a vacation at the same time. Funy thing was they both were still ploting a position and course, but that position did have no resemplence to reality at all. This went on for about half an hour before they got both back to normal. If you are navigating in confined waters like we were at the time, you realise what happened almost instantly. Offshore, I don’t know if we would have realiced what was going on.

Simon Wirth

John, this is most certainly the biggest risk of using electronic navigation. I, for one, tend to distrust the accuracy of the GPS below 100m. Witch makes me “unhappy” in any situation where there is less then 0.5nm to any dangerzone without a possibility to check by eye.
The best way to get a feel for GPS accuracy is to take a handheld/tablet out in winter, in fogy or low clouds and bad light. If you do this, like I did, in near white-out conditions, and just try to reach a waypoint you will understand why I am unhappy with only a GPS position. Normaly one can walk as long as one wishes without ever reaching the point. This experiment makes hiting a harbor entrance with GPS alone a really scary thing to do.

Greg Egilsson

Lot’s of free documents at the link below. Pilot charts, sailing directions, celestial nav tables etc. in PDF format. I learned navigation on paper charts many years ago, but have been using electronic charts on plotters for twenty years now as a commercial fisher/sailor . The good name brands are very very reliable these days. I never leave the wharf without paper back up but must confess I’ve not used them lately and yes the parallel rules have been seized for a few years now.



I’m still cruising local (Puget Sound/San Juans) in prep for making a left turn at Cape Flattery. I have a Garmin 120 and a brand new Garmin 76 (both came with boat; 76 has coastal charts). Pretty old school. Oh, did I mention I have charts. What I don’t have is a budget for chartplotters, ipad minis, faraday cages, more ipads for a backup. I will buy a sextant and continue to learn traditional navigation assisted by the Garmins (I use for vog, cog, and drift). Send me your charts, Pacific please. The only way I am going to get to play this rich person’s game is if I play a different version. I have a small boat (33′ Vanguard [thank you, Philip Rhodes]), so space for much electronic assistance is dear, but GPS, depth, and radar all swing into the cockpit. Buying sleeves and cases for charts in the cockpit and below. I really appreciate this site, not only for the wisdom and experience of John, et al., but for the sailors that join in the conversations. I don’t cruise the latitudes much higher than 50 deg N, but I definitely attain adventure.


Thanks for your kind reply John. I just checked West Marine and 12″ Raymarine network displays (they are not called chartplotters at this size) is $3700 and comes with nothing. Need to buy charts still, electronic though they may be. WA state sales tax would add another 350 or so; let’s be generous and call it $4k. No charts, no waterproofing, no sensors. That’s just for the primary. E-charts still need to be updated ($$), purchased for new areas. Add in back up (paper charts?), faraday cages, and rotating ipads and you are up in $10k land. That’s about what I spent for the boat. $10k buys a lot of charts and they can be corrected for free. I don’t mean to be argumentative, I just want to be able to sail safely and not have to go back to work to pay for navigation. If there are holes in my plan, I am more than open to constructive criticism. Thanks again!

ben garvey

Matt – would an old ammo box (easily found at your local Princess Auto Store) serve as a decent faraday cage? I don’t know that they are aluminum – might be light gauge steel (I haven’t put a magnet on one but will next time). They have a pretty good overlapping lid with positive latching, and the good ones have a seal too (which may break some of the electrical contact, but the hinge and latch are still conductors across the lid).


ben garvey

Ahh yes. I did read that post, but somehow missed that. ok, so wrap the seal in tinfoil or replace with conductive seal (available but expensive)… I wonder if you stripped the braided sheathing off Coax cable and ran the seal through it, then re-fitted it if one might regain good electrical integrity. Obviously waterproofing would suffer, but that’s less important.

Another cheapy faraday cage I discovered on my shelf yesterday – I have an aluminum legal size clipboard – full overlap lid, no seals, 1.5″ deep – enough for a hand-held gps, vhf AND ipad in a pinch. With a couple of good velcro or elastic straps wrapped around it to ensure the lid is in good contact I think it might be a poor mans solution. And – you can put small chartlets in a zip lock under the clip on the cover! Hard to test though…



Modern Chart Plotters in the Cockpit are a wonderful aid to Pilotage and Navigation but on our Cruising Yacht can only augment never replace totally the use of Paper Charts for some simple reasons.
We too have back up after back up for our Helm Mounted 12 inch Plotter by way of Computer and Spare Hand Held Unit. Yet when recently having suffered a knockdown in a Snowstorm resulting in the loss of all electrical supply the day was saved by being able to immediately pick up a chart upon which we not only mark our position hourly but will have plotted our proposed route before the start of the voyage, a quick glance at the Magnetic Compass and the chart and off one goes with less than one minutes delay allowing time to repair the electronics.

When we are threading our way through numerous Islands / rocks often marked by Vards , one looks out and ticks off each landmark on our Cockpit carried Chart as one passes with the result that there is no forgetting where one has got too and what may be coming up in five ten or even thirty minutes time.

The very act of plotting a proposed course results in one seeing and taking note of obstacles and ensuring that easy reference clearing bearings can be calculated not forgetting too contour lines to be followed.

Yes of course Plotters are fantastic, ours will even Plot a Course BUT there is still nothing more reliable than the Mark 1, 2 or even 3 Eyeball used in conjunction with a Paper Chart.


I just googled for a Raymarine c90w. It found it at $1,700 and it comes with all US coastal charts. We even had chart choices when we bought out plotters. I have the 90 in the cockpit and a 120 at the nav. Although I prefer the 120, the 90 is just fine for the tightest of spots. Boating is simply not cheap but $1,700 for the US ain’t bad.


We will and do use every aid including a Tablet with Navionics, Laptop with C Map Charts and a Helm / Cockpit Mounted Plotter that is available, however, short of a fire the only item that never fails is the good old paper chart.

On a more serious note , I have lost count of the times that I have been using a Cruising Guide / Pilot Book only to find that the Lat and longs when marked onto a chart have been found to be in error, whilst I know that with a relatively small screen when in putting way-points that the errors are not always picked up.
So whilst we could bat this one back and forth we would still be of the opinion that Electronic Systems should AUGUMENT not replace the Paper Type. krs james

bernard douteau

My backup is a laptop panasonic with it’s own gps (garmin) and
the coastal navigator program that has the advantage of active captain
resources and has different charts. It sits on the companionway hatch
when needed for landings or difficult spots/areas. The other advantage
is I can get info as we go on landing specs before we arrive (like cruising
book info) We do not really go offshore, mostly all coastal or short crossings. So electronics seems to be doing fine for us.
thank you for site that we follow at all times (member)
Bernard Douteau Adagio

Allan Juul Andersen

Hi John
I plan to follow you on your iPad back-up plan, but how do you charge it when you are out of power? (and thereby ability to start engine).
Thank you for a very interesting and informative site that I enjoy following as a member.

richard dykiel

I used chargers made by solio. Now my boat has a solar panel so it’s enough to keep my ipad mini plugged all day long. If I have a protective case that’s waterproof allegedly up to 6 feet, the power connection isn’t, unfortunately. But I was reflecting that, as soon as I leave the near shore for a passage, the ipad doesn’t need to stay in the cockpit.

Erik Snel

Hi John,

Good thoughts. I always carry paper charts, but I see them mostly as a planning tool and as the backup of my multiple backups.
As real backups I use an iPad and an iPhone. I do not share your concern about the need for waterproofing: my paper backup needs to stay inside, so why does the iPad need to be usable outside? For backup, inside use should suffice!
Power is another matter. For longer travels I own a battery backup for iPhone/iPad. This battery is hardly larger than the iPhone. Still, it packs a lot of spare energy: I used my iPhone connected to this spare battery while skyiing some weeks ago. A total use time of 6x 8 hours of skyiing, while keeping the GPS and a tracking app switched on continuously resulted in a half empty backup battery. So if the worst case scenario of totally dead batteries was to happen, I could most probably last 2 days with the iPhone switched on or a multiple of that plotting a course on a paper chart using the iPhone as a GPS device. Seems that should be enough!
Big advantage of these backups is I can (and have) shove them in the oven in no time, so no risks in an electrical storm!

Erik Snel

Hi John,

You are right, a waterproof cover for the iPad would be a good idea. As for solar panels, have those, but I was thinking along the lines of a total failure of the electrical system. In that case the backup battery combined with the iPad used once every day until shore is near would last very long…

richard dykiel

A lifeproof case for iphone 5s is $80. I don’t recall the prices for my ipads. I think that’s cheap insurance for delicate electronics, either on the water, or in any outdoor activity for that matter.

Erik Snel

Ah, that way. In that case I would definitely include a backup battery in the freestanding solar power system in case the sun does not shine for a couple of days…


WOW! So I just spend a few thousand EUR, heading to a RYA coastal yachtmaster degree, and finally being convinced that paper is king and absolute mandatory! 🙂 🙁
My opinion: I do have a 12 inch C120 Raymarine plotter: it’s not the fastest around but I choose it because it only draws 1A, compared to 2.5 for an E120. I find that a plotter nowhere gives you the same sense of oversight as a paper chart. On the other hand I wouldn’t like to miss my plotter at all.
Zooming in and out with a plotter can’t be compared to having a look at the map and plotting each hour your position.
So for me the optimal combination remains paper chart (which doesn’t have to be 100% up to date perse) combined with a plotter, and a ipad for back-up.
My fear is that “modern” sailors using only electronic devices could have less understanding of the parameters involved in sailing, as used in classical calculations for navigation, but I might be wrong.


I like the suggestions of using an iPad for navigation. We house one in a waterproof Penguin case and mount it on “Ram” mounts at the helm, under the dodger and at the nav table with usb power socket installed in several places. It worked extremely well when our plotter died.
Our favorite place is our Ram mount installation above our aft double berth. This gives us a media room and we watch movies in bed.

james peto

YES, YES AND YES AGAIN. Paper charts are not only the penultimate fail safe navigational / pilotage tool, ranking just behind the mk1 eyeball and should be carried at all times.
Prior to making passage the very act of plotting the proposed track on the chart concentrates the mind on all the various “obstacles”that may be put in ones way, so what ifs can be considered.
Whilst on passage marking vessels position compared to predicted quickly draws ones attention to possible future problems, change in current affect, leeway etc.When handing over watch, we sail two up, the marked chart acts a quick reminder of what has happened over the previous two hours.When approaching land the chart can be held up horizontally to eyelevel to enable identification of landbased marks.
We also, for difficult pilotage use a white board marked up to show the major points that we want to see and their respective bearings.
Having written all that, Plotters /electronic systems are fantastic

Simon Wirth

Hi John
A bit off topic, but your answer just got me wondering what the old vikings would say to your “traditional navigation methods”. Somehow, I think it would be interesting to hear their reaction. Everything depends on your perspective, doesn’t it?

Geir ove

We dont need paper charts.
i am wondering if we need the chartplotter at al ?
I find that charts on my I-pad gives me faster info, works better then the same charts i have in my plotter, So No paper, and nexst time no plotter, or maybe some new have turned up by then 🙂
We upgrade the charts online al the time, never did that on paprecharts. they stay old al the time.


Like many sailors we too haven an iPad with Navionics on board as a backup navigation system should the plotter die or should we lose power. But let’s say we lose power and can’t repair it for some reason, how would we re-charge the iPad? (Since we have Lithium batteries this is not completely unlikely. I know, a questionable choice in term of fault tolerance and repair-ability. But that’s another story …)
I think the iPad with GPS always “on” would run out of steam in 3 or 4 hours. And then, how do you re-charge it without power?
In order to solve that problem I invested about 40 dollars for:
1. a USB-Charger that takes as input anything between 12 and 24 volts DC. It costs 6 dollars and we could wire it to a starter battery or to one of the solar panels (they provide 17V each) in order to charge the iPad. I bought two.
2. We have 6 Makita cordless tools on board and 4 big 18V Li-batteries to share between them. Makita makes an USB-adaptor, that you can slide over one of these huge batteries and that provides 2 USB-charging-bays. I think (without having tested it) that one full battery pack could re-charge an iPad at least 5 times. I imagine other power tool manufacturers have a similar gadget.

Of course we also have a handheld Garmin GPS that runs with normal batteries and a lot of spare batteries and paper maps. This is for the worst case to have at least a GPS position.

Marc Dacey

While I haven’t actually done this, I believe it is possible to clip together a series of AA batteries to which you could attach a resistor and a USB cable. That could charge any device, depending on the resistor and the draw required.

It’s a fussy way to do things, but it would work in an emergency, like charging a satellite phone.

Jim Allen

Getting ready for a trip and want to include a Faraday cage as part of our lightning preparation kit. In John’s great article on “Backup systems, do we need paper charts” there is a link re Faraday cages “see post for how to build one” – I believe this is from Mat. Problem is, when I click on the link and read everything, can’t seem to find this post beyond mention of an aluminium box with continuity and no isolation gasket. Am I missing something or maybe this is the description of how to build one?
Would be interested in comments from people who have built their own and how they went about it – design of lid etc to get continuity and also how they handled the cage grounding issue and any other details. Maybe someone has found a properly built effective commercial unit that is not too outrageous in price?