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Nuno on a Mac

For some time we've been working to deliver something that a lot of people have asked for, Nuno on a Mac.

The percentage of people using Macs as opposed to Windows PCs is often said to be a little over 10%. But our research and experience suggests that amongst leisure sailors it's closer to 30%. That's why we are doing it.

This will be what software companies call a beta release. A beta is a test release - not completely untested but no guarantee that everything will work for everybody (it's actually rare that any software is released with that level of confidence unfortunately, there's always such a great range of computers and configurations out there).

Releasing a beta gives people a chance to try things and for companies to get feedback, did it work? how did it work?

Beta releases are a little experimental and so not for everyone.

It's been harder than we expected. We've had to make some changes to the software to make it work, we are using a software platform called WINE. Wine is a long running software project that allows Windows programs to run on OSX and Linux. Unlike running Windows software using Parallels, Bootcamp, VMWare and so on you don't need to buy a Windows licence. It's just a download and drag to Applications.

This has ended up being one of those long promised things that has taken longer than we hoped. But it really is real. Coming very soon...

Placing Waypoints

I spent a good few hours with yachting and powerboat instructors this weekend. One of the things they try to emphasise to their students is that waypoints on a route should be carefully placed to make that route easy to execute. 

It's a good idea to link a waypoint to something that the person at the helm can see. This defensive approach to passage planning builds in an easy way to keep a check on the GPS feed and to make route that can be sailed even if the GPS stops for some reason. Looking out of the window rather than at a screen is safer and more pleasant as well. 

If you can ever place a waypoint so that something conspicuous is abeam you can keep things simple in planning and execution - no need to draw pencil lines on the chart and no need to take bearings with a handheld compass whilst sailing. To make this simple, Nuno draws grey lines to either side and forward in a continuation of the route leg whilst you are making a route or adjusting the position of a waypoint on a route. 

London Boat Show 2015

We were at the London Boat Show 2015 last Monday (12 January 2015). The trains were having a difficult time Frown so it was something of a flying visit. Hello to everyone we talked to!

Because the RYA Training Chart Plotter is now included in all RYA Training packs we spent a lot of time on the RYA stand (not all of the time was spent playing the powerboat simulator, though we enjoyed that.)

The training plotter is based on Nuno and early feedback has been good. We believe it will be a great aid in communicating safe navigation to trainees around the world.

It was around this time last year that we were getting together the agreement for CHERSOFT and the RYA to work together on this. Developing software can at times be fraught - but developing the plotter went smoothly. Thanks to everyone at the RYA for their help with that.


Happy New Year

Happy New Year to you all from the Nuno team!

It's about the time of year we change the name of the application.

Last year it was called Nuno Navigator 2014. This year we are going for Nuno Navigator 2015.

Best wishes for 2015...

Changing the Nuno application caption

The Black Rose

Black Rose is a 52’3” wooden gaff-rigged ketch built in 1999 at Maylandsea in Essex, UK. She was designed by her owner Michael Emmett (assisted by many good sailors) and is based on the traditional oyster fishing smacks which were to be found around the southern North and Baltic Seas three or four centuries ago. 

Michael will be visiting the Baltic again during 2015. In addition to tending to the flax sails, cast-iron windlass and varnish work, Nuno Navigator will be on board to provide continuous GPS plotting of positions on a standard laptop PC alongside some sat comms wizardry from Navidatum. The Splice M2M terminal gives Michael satellite messaging, weather forecasting and lots of other features while he is out of cell phone coverage. It also provides a GPS NMEA feed.

Tim Scott-Douglas went on a test trip down the river Deben in darkest December (0°C, 32°F) to prove the system and enjoy a weekend’s sailing. 

Michael has been sailing around the Thames Estuary all his life in all weathers and knows it like the back of his hand. He has also been to Holland, Germany, Belgium and France many times over the years but this time there will be new places to visit and changes such as colossal windfarms offshore to plan for. Easy access to the charts is essential as is communication between navigator and helm.

The WW1 compass box is just the right height!  

We started off by putting a laptop running Nuno above the chart table. Paper charts below. The paper charts are staying for now. 

Though cold it was a bright crisp December day in Suffolk and after sailing under canvas all the way down the river to Felixstowe Ferry we turned back up river with the young flood tide. 

Having passed straight by two pubs on the way down, third time lucky on the way back we managed to persuade Michael to anchor at the Ramsholt Arms for the night. 

The Ramsholt is remembered fondly by generations of sailing families spread all over the world, many of whom will never have seen it in mid-winter with a log fire blazing. A memorable evening and then back aboard for one of the skipper’s (nearly as) famous suppers. 





I bet he didn’t believe his eyes at sunrise either!


We have another instance of electronic charts being suspected of a role in a marine accident. The USS Guardian ran aground at 0225 17 January 2013 (1825 UT 16 Jan 2013) on the Tubbataha reef in the Philippines and it looks fairly likely that ignorance of horizontal datum and failure to ‘maintain a proper look-out’ (IMO COLREG 1972) were to blame. There must have been a series of ignored alarms and indications that all was not right, but somehow the app (DNC plotter) was believed.

“Since DNC mapping is used for safe navigation by Guardian and other U.S. Navy ships, Navigator of the Navy Rear Adm. Jonathan White also today released precautionary guidance to all Fleet and ship commanders. White’s message states, “initial review of navigation data indicates an error in the location of Tubbataha Reef” on the digital map.

The Avenger-class mine countermeasures ship had just completed a port call in Subic Bay and was en route to Indonesia and then on to Timor-Leste to participate in a training exercise when the grounding occurred.”


The source data for Electronic Navigational Charts (ENC) as stipulated for ECDIS and presumably the imageDigital Nautical Charts (DNC) as used by the US military comes from National Hydrographic Offices and is shared by agreement between friendly powers such as UK and US. Here are some snapshots of the paper and ENC charts of the Tubbataha Reef in the Sulu Sea. The data includes centuries of observations and measurements, often with supporting notes on validity and advice on use. It is perilous to ignore the advice but in these days of an app for everything and continuous warning messages from gadgets, the critical details is often lost.

The following are all current, corrected charts which would pass any Port of Flag State inspection. They represent more than enough information for any self-respecting navigator to cross the Sulu Sea without running into anything, the cautionary notes are well-known to seafarers as can be seen here in the continuous series of chart notes on surveys dating back to 1850!


Chart 4507 1:3,500,000 Philippines to Bismark Archipelago


The vessel was on passage from Subic Bay in Luzon north of the Sulu Sea to somewhere in Indonesia to the south. Plenty of sea room to avoid the reef and in an area well known for its sensitive natural environments.

The next bit of his intended voyage would have been in the Archipelagic Sea Lanes around Sulawesi and East Timor/Papua New Guinea to take part in a training exercise.



Chart 3811 1:500,000




Chart 967 1:725,000






Chart 3483 1:1,500,000



That note on the chart say “reefs rep to extend 1.5 miles seaward 2005”




clip_image004What was he doing within ten miles of the reef in the pitch dark - the moon’s altitude was -57° at the time? It was virtually low tide but with only a metre or so range that would not have made the difference between sinking or floating.

Below: ECDIS ENC showing a point plotted using the same co-ordinates. It would be interesting to know the co-ordinates which they were working to.

clip_image002[17]Never mind faulty DNC data or 1.5 mile errors, this is an example of ECDIS assisted casualty which would not have happened if the navigating team had looked at all available sources of information. Not just charts and publications but radar, echo-sounder or even looking and listening out of the window which I am sure told a vivid story at sunrise! Where has this vital information been lost (lost may be the wrong word here as there has obviously been a decision not to include it in the data for the ECDIS or DNC apps).

There was a lot of talk about ‘smart’ vector charts (now known as ENCs and DNCs) versus ‘dumb’ raster charts (ARCS etc) some years ago and a lot of spurious assertions as to the intelligence of the data. It makes little difference if the app is running on a mobile phone, am ECDIS or a nuclear bomb-proof naval command and control system, the only intelligent element of the system is the human navigator.


Teach the navigator how to navigate, not how to use an app.


I am guessing that he was trying to go east-west through the channel about 1.52nM north but just got too close to the reef - same school of navigation as Captain Schettino of the Costa Concordia? clip_image010

It would have been no significant deviation to leave the lighthouse to port, he was only 4 nM from it when he hit the reef so he must have been able to see it out of the window as well as on radar. I don’t actually think he was show-boating as it is an uninhabited atoll and it was dark, but he chose to believe his DNC instead of everything else.


There is no ‘error in the location of the Tubbataha Reef on the digital map’, it is referenced to a different horizontal datum. Digital maps can never be any more accurate than the source data which they have been constructed from and it will be a while before the remote (from US and Europe) parts of the world are referenced to the WGS84 spheroid.

Even state of the art cutting-edge aids to navigation apps require a true understanding of how they work and safety back-up using MKI eyeball pointing out of the window.




Digital Certificate Magic

Nearly all the code that comes out of CherSoft is digitally signed. You might reasonably ask ‘So what does that mean and why should I care?’. Well, the signature provides proof that the code came from CherSoft. It also proves that the code has not been tampered with. So, not only can you be sure that you are getting exactly what you think you are getting but also that nothing has been added (like a virus) or taken away or fiddled with. This is actually a pretty strong guarantee. It is also pretty important. In fact it is considered so important that most of the requirements for handling and checking digital signature are built right into the Operating System.

Here is some technical stuff. It is easy to copy and edit files – so how do digital signatures prevent tampering? The clever bit is the use of asymmetric cryptography. Now the math behind this is a bit evil and well beyond me, however the practical upshot is that it is possible to encrypt something with a private key that can only be decrypted with a public key (a key is a string of digits that is used in the encryption algorithms). You can’t use the public key to work out what the private key is (that’s the asymmetry bit). Signing the code involves creating a digest and then encrypting this with the private key. A digest is  a summary of the code which will always change if the code changes. Imagine taking every 100th letter from a book. If the book changed then the sequence of letters would change. A digest works (very nearly) like this. It is much shorter than the whole book so it can be encrypted or decrypted quickly.

So if we give you our public key and sign the code using our private key then you can use the public key to be sure it came from us.

How do you get our public key? Easy – we put it into a certificate. This is a file which contains some information about us (CherSoft), an expiry date and our public key. When Windows checks the files before installing them it looks for a signature and checks it against the certificate. The certificate is appended to the code but you can, if you want, download a copy of it here.

Now if you are paying attention then you should be asking ‘ah ha, but how can we tell the certificate is genuine?’. Maybe you have landed with some virus ridden code and they supplied a certificate with it as well. This loophole is closed by digitally signing the certificate. We don’t do this. Verisign do it for us. In fact we pay them quite a lot of money to do it for us. Verisign sign our certificate and then the public key to  verify that signature is stored in a Verisign certificate. Verisign are known as a Certificate Authority. They sign a lot of certificates and their public key unlocks all of them. The certificate containing imagetheir public key is known as a root certificate. You can trust it because it comes from a well know source and it is ubiquitous. If someone attempted to forge our public key certificate they would not be able to use the Verisign certificate because the private key for that is kept very private. So the certificate chain leading to a trusted root certificate is your guarantee that the code is exactly what it is supposed to be.

The CherSoft certificate is signed by an intermediate certificate which in turn is signed by the root certificate.

This stuff is a bit technical and involved. Fortunately it is also quite effective and, for the most part, handled by the Operating System (Windows) in a way which makes downloading and installing stuff safer. If you ever see a message along the lines of ‘This code comes from an untrusted source’ then you should make sure that you are confident that you know exactly what it is before going any further.

The Verisign certificate needs to be installed on your computer. So how does it get there? Turns out that there are several mechanisms of which the easiest is that the Windows Update service will do it for you. Keep Windows up to date and there will not be any problems (not this sort of problem anyhow). If you do not update your PC then a problem can arise because the one of the root certificates becomes out of date. We do see this occasionally especially on shipboard computers which never get to see the Internet from one year to the next. If your root certificate is out of date you may get to see this:


The solution is to download the missing or out of date certificates. You can get the Verisign intermediate certificate here and the Verisign primary root certificate here.

Copy the information for the Certificates as explained on the web page. Then paste them into plain text files (use notepad) and save it to a file whose extension is .cer.  Follow the instructions to create a .cer file for each missing certificate. Copy the certificates to the PC. Right click and choose ‘install certificate’. This requires Admin privileges. Choose ‘Automatically select the certificate store…’ when asked and accept all other defaults.

If you want to check signature on our code manually then download the Nuno Navigator installer and right click on the file (called nunonavigator.exe). Click on the Digital Signatures tab.


Click on the CherSoft Ltd signature and choose details.


Automatic Identification System (AIS)

Each vessel fitted with an AIS transponder transmits its identity, position, course, speed and other information over a VHF channel. AIS1This is compulsory for vessels over 300 tons and all passenger ships. Quite a lot of other vessels carry them as well.

So if your boat has an AIS receiver on board you can track these vessels if they are in range, typically 20 miles or so. If the receiver has a display at all it is usually a bit rude and crude – the real trick is to feed the AIS information into your chart display system. Now you can see the AIS targets overlaid onto your navigational chart and this starts to get useful.

AIS was intended and designed as a collision avoidance mechanism however you really need a graphical chart based display to properly realize this. Nuno™ now supports AIS (hooray!) and makes a great way to display the information.

Even on a smaller boat there is a lot to be said for getting an AIS receiver. They are pretty cheap these days and benefit in terms of situational awareness is brilliant.

Configuring AIS in Nuno™ is pretty easy. You need an AIS unit with a NMEA output and then you just plug it in. That’s it. Depending on your set up the AIS NMEA stream may be multiplexed onto your GPS feed or it may be a separate connection. Either way just plug it in and Nuno™ will find it.

AIS targets are displayed as little green symbols with a vector arrow representing speed and direction. Ticks on the arrow are at one minute intervals. Hover the cursor over the target to see additional information such as name, destination and cargo. The scope of the information being broadcast can vary quite a lot.

AIS5Here is a really handy technique: Create a pencil line and drop one end onto the marker for your boat and the other onto an AIS target. The line will display range and bearing to the AIS target. Even better the line will ‘snap’ to your vessel and the AIS target and update as they move. Very useful for keeping an eye on another ship.

Nuno™ with AIS capability is being released soon. Very soon. Maybe even today. This is available as a free upgrade to all users with a current license. There are lots of other improvements in this release and some great new features just around the corner.

How do you get it? Easy. Run Nuno™ up on a PC with an internet connection. If an upgrade is available it will tell you in the Support Centre pane and there will be a download link for you to follow.

Looking out of the window

P8049657A concern commonly raised during discussions around electronic navigation systems is the way that they can contribute toward incidents. The scenarios usually revolve around lack of training and an over reliance on the computer software. In fact several grounding incidents have been directly attributed to this. In each case the ECDIS was not correctly set up for the conditions, presumably because it was not well understood. At the same time other more traditional approaches to navigation such as looking out of the window were being neglected. The inevitable result is a lot of unhappiness.

So what is really going on here? How come a system which is designed to make navigation safer is causing problems instead?

First off, we should probably assert that electronic chart systems are, for the most part, a big benefit. Very basic properties such as accuracy of positioning and ease of chart updating set such systems head and shoulders above paper charts. I can go on with a long list but you probably already know it. So where is the downside? At CherSoft, there are two issues that we are very aware of: first up the screen is not as big or clear as a paper chart, secondly the user interface can act as a barrier. Good software should be mitigating these issues by making optimal use of the screen real estate and by being easy to use. Obviously, if the software is easy to use then training is less of an issue.

But there is another angle to this.

A long time ago when Microsoft Word was a DOS application I was asked about how to set up the page layout. I had never looked at this at all before but I gave it a go and it only took a few minutes to get sorted. The secretary was impressed with my knowledge of Word. Of course I was actually making it up as I was going along but the results were fine so that didn’t matter. I’d never had any training on Word and I did not have a detailed knowledge of its settings. That was not so important because I did know the principles behind it and understood the general approach of the User Interface. My knowledge was to do with the domain rather than the details.

Understanding navigation systems is the core issue. Many systems, particularly the professional, type approved ones, are devilishly difficult to use. This may surprise you. Certainly if you had paid several thousands for a state of the art system then you might hope it would be quite approachable. The trouble is that not only are the User Interfaces, for the most part, quite primitive, but also the mechanisms around obtaining and updating charts tend to be complex. The latter is mostly associated with the dragon of Digital Rights Management. These factors mean that training, of necessity, has to be concerned with a lot of detail.

We think that the navigation system should be easy to use. It should be sufficiently easy to use that someone with knowledge of navigation and some elementary computer skills should be able to use it. I am not going to claim that Nuno™ achieves this yet, but it is what we are aiming for. This still leaves a gap though. It still leaves space for the fatal over-reliance on computers. Perhaps this is more of a cultural thing than a specific training issue. I suspect that the more you know about computers and their weaknesses then the less likely you are to drop unsuitable responsibility on one. Another way of looking at this is to consider that a computer, however clever it appears, is just a tool.

I think there needs to be convergence. The electronic tools should be useful without demanding specific knowledge. At the same time the limits of the tool should be understood at a domain level rather than in terms of the detail. My hope would be that the increasingly computer savvy people driving the ship will be using these tools so that they can spend more time looking out of the window rather than less.

Joined up charting

Charts are square, countries aren’t, it’s a problem. There may be a vision of a utopian world where country boundaries are straight and align with a geodetic grid but the reality, as usual, is much messier. The tricky bit is that each national hydrographic office will create ENC cells with bits missing. The political ramifications of drawing a map of someone else's country can be severe. Politicians just don’t like this sort of thing and Google have managed to upset people to a remarkable degree by misplacing the odd line. So the only sensible thing to do is to create chart up to the national boundary and then stop. Of course by safe I mean politically safe. For the mariner it is a pain in the transom akin to sailing off the edge of the world.

US-Canada ENC Harmonisation

This means we end up with multiple ENC cells of the same area at the same compilation scale but from different providers. The reason you might care about this is that you could easily end up with duplicate or similar features from both cells overlaid on each other. Depending on how your chart display software renders this it will probably look a mess, could easily be confusing and might even be dangerous.

Fortunately the good people at the International Hydrographic Office have already thought of a solution to this. Unfortunately it requires a degree of international cooperation and we (I am speaking for the whole human race now) are not very good at that. None the less several countries have been giving it a go following the principles of the Worldwide Electronic Navigational Database or WEND. This is a great idea and would be even better if it worked. I am not saying it won’t work but there is a way to go yet. One small step in the right direction has just been announced by NOAA and the Canadian Hydrographic Service. They have conceded that the boundary between the US and Canada is not straight so they have agreed on using a wrinkly one instead.

ENC cells are often cataloged and managed by the coordinates of the cell corners. This is fine most of the time and implies that the cell is square. However within the cell is a coverage object which really defines the shape of the area covered by the cell data. This can be a polygon of as much complexity as needed. So if two countries cooperate they can arrange the coverage boundaries along the international border, each country then charts its own bit and everyone is happy. The UK and France are a good example of where this works well. What is happening up on the Canadian border seems to be a little different though. They are still dividing up who does what but, see the above diagram, they are not following the border. Instead they are making sure the the cells will fit together properly but Canada is charting some of the US and visa versa. Why are they doing it this way? I have no idea. Please tell me if you can shed any light on this. Pragmatically the reason does not matter too much. The end effect will (should) be a set of ENC cells which join up nicely.