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Almost there

The first full release of Nuno™ is coming soon. Very soon. Within a week even. It has some great new features, some great improvements and some great bug fixes. Ok, so it is not so great that there are bugs to fix but it is important that we fix them. It is impossible to write code without bugs and anyone that says otherwise probably doesn’t write code.

Here’s a run-down of some of the things we’ve improved:

Overview. A small scale pop-out window with data quality and other overview type information on it. This was discussed here.

Anchoring mode. This is a display setting to show a bit more detail on the chart. Useful if you are maneuvering in to tie up but probably a bit too cluttered for regular use. We’ve done a lot of work on trying to manage clutter in chart displays. It is one of the big problems with vector chart systems.

Track log. Nuno will now maintain a record of your vessel track.


So now you can see exactly where you have been. You can save portions of the track in case you need a permanent record.

Chart Updating. This is getting better all the time. Our aim is to make chart updating so simple that you will, with almost no effort, have a complete set of up to date charts all the time. We are also working on reducing the time taken to update charts.

That is just a sample. There are lots of small improvements and features which all go towards making Nuno a better navigation system and better to use. We have lots of improvements in the pipeline as well. Over the next few months we will be adding support for AIS, Active Captain and others.

What features would you like to see? We’d really like to hear from you.

In the meantime the beta program is still running and as an added incentive for anyone who has shied away from trying out the beta so far:-

Anyone who downloads and activates the beta version before we launch the full version will get 50% of the purchase price of the full Nuno.

Details about the costs are here. The bottom line is that it will save you $50. Even I think that is a pretty good deal. Downloading and activating the beta is free. No cost. No obligation. But you need to act soon because this offer is only until the full version of Nuno is launched and like I said – this is going to be soon.

iPad route monitor

Prolific marine blogger ‘Panbo’ reported that some of our competitors were doing interesting things with iPads and Windows based navigation systems. Andy Nibbs loves his iPad so he went off to investigate…


The iPad is ideal for an extra view on a Nav system. It’s a general purpose device when away from the boat which eases the sting on your wallet. It has a pretty good bright display and you can made it more rugged with off the shelf stuff. So you can have it in an exposed position next to the wheel while the laptop is in the dry below.

There’s a lot to be said for using an iPad in this way. The iPad is battery powered and connects wirelessly so it can work as an extra display on deck whilst your laptop is kept below. Note that you need a WiFi connection between the iPad and the Windows computer and a suitable app to configure your iPad as an additional monitor. Waterproof cases start at around $20.

The navigation software doesn’t need to do anything special – just work properly with multiple monitors. The iPad looks to your PC like an extra monitor.

Nuno’s route monitor view is just right for putting on an extra display.


I’ve tried iDisplay and Maxi Vista (both about ten dollars) and they both seem to basically work. Refresh rates aren’t the same as a real monitor.

iDisplay allows you to do some mouse work on the iPad display which is useful but I recommend using the iPad mainly as a display only view whilst a passage is underway. Your laptop’s display is probably better for passage planning.

Maxi Vista seemed to cope better with me checking my email on the iPad and then going back to it but it didn’t allow me to do any mouse work using the pad.

For both apps, you buy the app for the pad and it tells you what to do on the PC – which is to install some software to handle the PC’s side of the connection. Once that’s done, you run the app on the iPad and the app of the PC either detects the iPad and everything springs into life or you have to do something manual on the PC to start it up.

The iPad and PC need to be on the same network. That can be a peer to peer network with just a laptop and the iPad.

(Note: This post was written in 2010, there is a wider range of apps to do this now).

If the software is hard to use then you are going to need training

There is a lot of talk about ECDIS training at the moment. In the next few years ECDIS will become mandatory for quite a wide range of commercial vessels. Clearly having this kit on board is of little use if nobody knows how to use it and so the requirement for training is becoming prominent. mca_certificate_240x159

The argument assumes that the ECDIS cannot be used adequately without appropriate training. This is probably not a bad assumption because the usability of commercial ECDIS software tends to range from difficult to verging on impossible. This may surprise you. Expensive software doing an important job on what may be a large and very expensive vessel. Surely it should be designed to be easy and straight forward to use? Oddly enough this is often not the case. There are several reasons for this:

· The standards, specifically ISO61174, does not lend itself to useable software. This is the performance specification for ECDIS. It is over ten years old and is very detailed. Naturally it is based on ideas and technologies that were prevalent ten years ago. Ten years is a very long time in the computer world – we are talking pre-Windows 2000. What is more at the time the standard was written there was not much around in terms of marine navigation systems and chart data. So rather than drawing on best practices and experience the standard needed to present a vision of how the committee thought that navigation software was supposed to be. Now I don’t actually know how the committee was chosen but I would guess that there were very few computer usability experts amongst the members. Even if there were then they were faced with an impossible job no matter how good their crystal ball was.

· So designing ECDIS compliant software that is also usable is difficult in the first place but it gets worse. Given a realistic situation of limited budgets and resources the focus of the development effort tends towards compliancy issues. Usability is a secondary issue since unless the ECDIS can be certified as compliant with the standards it cannot be sold as an ECDIS.

· Actually getting the software certified is a time consuming and expensive business. I am talking many months and thousands of dollars here. It is not trivial. Once the software is certified then it cannot really be changed without being re-certified. This situation does not lend itself to the sort of on-going development necessary to make genuinely user friendly software. In fact it does not lend itself to any sort of development at all. One of the more popular ECDIS systems around at the moment is actually based on Windows NT4. Remember that? Yes, an improvement over NT3.51 but still a tad short of sparkling when it comes to usability considerations.

· Ship owners are a tight fisted bunch. They typically they will not spend a penny more than necessary on equipment so as long as it meets the regulations. At which point it is usually the cheapest system will do. I am not saying this is wrong, running a ship is a fantastically expensive business, but it does tend to make for comparisons based on simple cost rather than other factors. A particular company’s software may be easier to use but if it is more expensive than its rivals then it will be hard to sell.

Hopefully you are getting the picture now. In an attempt to make ECDIS ‘correct’ and sufficiently similar between all implementations the international regulatory bodies have completely shot themselves in the foot. They have created an environment where the bulk of the development effort and costs are aimed purely at achieving ECDIS compliance and all other considerations fall by the wayside.

S-100 is the chart data standard intended to replace S-57 at some point in the future. The groups working on this have recognized that a typical ECDIS can be a bit tricky to use. They have also noted that each ECDIS tends to be tricky in a different way so they have come up with a solution called ‘S Mode’. The basic idea is that every ECDIS has a button which will set it into S Mode. In this mode the controls, menu options, settings and so on will be exactly the same irrespective of which company made the ECDIS. This is such a beautifully naïve notion. It says ‘we’re a bit scared of this software so let’s make it all the same’. Of course any company developing ECDIS will implement S Mode and probably stop there. Where is the incentive and budget to do anything more? Where is the competitive edge? It all boils down to cost, how else do you differentiate systems that all look and feel the same? And so we arrive at a dead end which ensures training will always be required.

motorola-dynatac-8000xThere is only one way to make software more usable and that it to allow software developers to experiment. They have to try out ideas and find out what works. It is very difficult. In fact it is amazingly difficult but we are making progress. There is still ample scope for improvement but at the same time I feel no need at all for a training course in how to use my iPhone. I doubt that many of the millions of iPhone users do. By comparison my last car, which was a few years old, had an early mobile phone in it (this is back in the days when ‘mobile’ actually meant ‘semi-portable’) and no, I could not actually make the first phone call without consulting the manual. That phone and the ECDIS performance standards come from the same era.

Nuno does not come with any training courses. This is not a declaration of irresponsibility but because we don’t think it needs one. It is not technically an ECDIS but it will do pretty much anything that an ECDIS can do and in most cases it will do it a lot better.

Scale and Purpose

Here are some thoughts from Andy about what happens when we change the display scale.


What is the difference between a chart used at 1:1,000,000 and one used at 1:10,000?

The most obvious, for charts of the same size, they cover very different amount of area.

The actual numbers are staggering. Consider a chart drawn at a 10th of the scale – a length on the ground is displayed ten times shorter. This is ten times less detailed on both axes – one hundredth of the area. An area that was represented on a screen of 1 million pixels (a typical laptop) now has to be represented in only 10,000 pixels! That is a serious reduction. It is just 100 pixels by 100 pixels.

Image at 1:10,000clip_image002

Image of the same geographic area at 1:100,000


Incidentally, the range of useful scales for marine charts is about 1:2,000 to 1:20,000,000. That is an area ratio a million times greater than the above example.

The less detailed one has to leave a lot out. Otherwise it would be a sea of overlapping symbols.

How do we choose what to leave out?

The cartographer does this.

Traditionally, paper charts at different scales were quite separate. The cartographer drew each one by hand, more or less independently. Before even getting to the point of creating detailed charts, lots of decisions have already been made about which areas to even bother with. The mid oceans are only charted at 1:3,500,000 or worse because it doesn't help the mariner to have more detail. There is nothing to hit. It is 7, 14 or even 28 days to land. The detailed charts were only created for navigationally interesting places, ports, narrow channels, the coast because we don’t want to hit it.

With electronic vector charts, the attraction from the chart producer’s point of view is to have a single database of chart data and publish it at different scales – thus reducing the number of layers of chart that he / she has to maintain. In principle, you might feel that this approach allows you to produce a chart at any scale. This is re-enforced by the ability in many navigation programs to display the chart at any scale. But I don’t think this really works.

For a start, the detailed information required to make detailed charts still only exists for the interesting areas. Without that information, a detailed scale chart doesn’t give you any more information, it is just bigger. This is exactly the same as with town street maps. Once the scale is detailed enough to include all the roads and their names, you don’t gain anything – that bumper sized street guide just uses more paper to display the same information in a more spaced out way.

Continuing with the road atlas theme, we have different types of map for different purposes – from national freeways, through state and county maps to individual town plans.

Navigation charts are just the same. In ENC vector charts we have these navigational purposes







Their purposes are, hopefully, fairly obvious from their names. They have a very commercial ship feel to them though – were does that beautiful cove with a sandbar across the entrance fit into the scheme? – it needs a detailed chart, but isn’t the sort of place that commercial shipping cares about. Well, in US waters, Approach is actually more or less continuous along the coastal strip. Harbor also covers a lot more than just harbors, covering a substantial fraction of the coastal strip. So really the navigational purposes are more like scale bands.

Paper charts are also purposed, though, as they are selected manually, it wasn’t so explicit – you just pulled the relevant ones out of the chart drawer - a passage chart for the middle and a harbor chart for each end.

Now look at an electronic chart display. How do we choose the right chart, the right navigational purpose now?

Well, it is a trick question, because typically, you don’t; the computer decides. It switches between purposes as you zoom in and out. This explains why the display changes by more than you expect for some zoom steps. It has just changed navigational purpose.

It is obvious that this will not always do what you want. The computer does not fundamentally know what your current navigational aim is – so as you sail along the coast, it will tend to display harbor charts for the ports you are merely passing by.

The alternative would be to choose the navigational purpose manually – so you always get what you ask for (which might not be quite the same as want you want, or even what you need).

Now we can explain why we don’t do that.

Assume you have a button for each navigational purpose. Say you press “Approach”. The computer displays Approach ENC only. If you are zoomed in to a scale of 1:2,000, you will see a small part of a very coarse chart. If you are zoomed out to a scale of 1:1,000,000 you will just see a few small areas of mush – chart that is so scrunched up you can’t read the detail it contains – and most of the screen will be blank because approach data only exists for the coastal strip. At some scale in-between, you will see a useful Approach chart.

Assuming that we don’t think that computers suffer when we make them work harder, the computer can do much better than this – it can automatically display the less good navigational purposes underneath the approach chart. And it could indicate where there are areas of a more detailed navigational purpose available.

In practice, indicating the areas where there is more detail does not help much – it is usually obvious from the chart where the coast is – that is where the more detailed purposes will cover. There is little point drawing a more detailed navigational purpose when the scale is such that it will be too scrunched up to be legible. It is better to display a less detailed navigational purpose that is nearer to the display scale. So the computer ignores ENC data that has a much more detailed compilation scale than the current display.

In contrast, it is always worth displaying the less detailed purposes underneath because they will still give some context however un-detailed they are – after all, blank areas of screen give no information at all.

Given these rules, if you press the button for the most detailed navigational purpose, Berthing, the computer can automatically display the best ENC data that is available for the current display scale.

In Nuno we decided that this was want you would want 90% of the time, so the complication of having all those buttons was not worth it. Pressto – an automatic system that almost always does want you want, and on the occasions when ideally, you would prefer something slightly different, it errs on the side of safety, by displaying a slightly more detailed chart.

Navigational purposes are the main reason why the content of the chart changes at certain scales. As you zoom in to a scale where it is worth displaying a more detailed navigational purpose, the chart is completely replaced by the new navigational purpose; it might be from a different survey; certainly the person who compiled the chart will have included more detail, both in objects such as buoys and in the wigglyness of the coast and depth contours.

For what it is worth, here are the scales of each navigational purpose…

Nav Purpose

Normal scale range



1:1,100,000 to 1:4,860,000



1:500,000 to 1:1,200,000



1:180,000 to 1:600,000



1:80,000 to 1:120,000



1:10,000 to 1:50,000


A few at 1:5,000

Berth (only 2 cells)



Because there is such a wide range of scale within each navigational purpose, it is possible to find an area and scale combination where some of the chart is displayed at one navigational purpose and the rest at the next one. This results in a discontinuity in the chart at the boundary because of the different surveys and detail level in the two purposes.

To summarize this discussion. The software tries to display the best detail available for the current scale. Knowing about the mechanisms involved in the choosing the data to display allows you to understand the discontinuities that sometimes appear and make the best use of the electronic chart.

Nearly a Source Data Diagram

Many paper charts include a Source Data Diagram (SDD). This is small inset displaying the charted area which indicates something about the origins of the information used to compile the chart. There can be some important stuff here.


This SDD shows that some of the soundings come from a lead line survey in 1832. In other words... and think about this carefully ... a hundred and eighty years ago somebody stood on deck with length of hemp rope with knots or marks on it and a heavy weight at the end. From the numbers he shouted out you are going to decide if there is enough water to avoid grounding your boat. To be fair most commonly used waterways are much more recently (and accurately) surveyed than this but even so it can be worth checking. The chart may be completely up to date but the original survey could have been a long time ago.

Of course with your shiny electronic charting system you may think that this sort of consideration is not an issue any more. Sadly this is not true. Most electronic charts are created from paper charts and this will probably be the case for a while. Now clearly the underlying accuracy of the survey data is a concern. The designers of S57 had a think about this and came up with the notion of a ‘Category of zone of confidence in data’. This is chart meta-data - data about the data. Areas are defined and for each area the quality of the underlying survey data, the Zone of Confidence (ZOC) is classified as one of:


This looks quite promising. Instead of telling me something about where the data came from they are going to tell me directly just how accurate it is.

These meta data objects are designed to be used at the compilation scale of the chart however this does not seem quite right to us. The information is really part of an overview of the chart, a summary, so in Nuno we are introducing an overview window. This displays the Zone of Confidence areas and has some other nice uses too.

A second potentially useful bit of information for the overview comes from 'Nautical publication information' objects. This is more meta data which is a reference to a specific paragraph from a nautical publication. Quite usefully this is often a note about the paper chart which was used to create the electronic cell and in particular the source date of the paper chart.

So in Nuno we have put this information together into a nice little inset window which can be easily displayed or dismissed. It gives you a handy overview of the main chart view and its surrounding area. It also supports panning and zooming which can be a neat way to move the view around larger areas. 


You can click on the little button I have circled in red to make the overview disappear. Technically this is called an affordance (just in case you wanted to know).

Sad to say there is small hiccup in this scheme and this is because of another value for Zone of Confidence which does not appear in the table above. The value is U and this means ‘data not assessed’. Which is to say that the creators of the electronic chart cells have chosen not to specify anything about the quality of the chart data. To my mind it is a bit unfortunate that this value even exists however it gets worse because for the most part all the NOAA data is classified as U. A few newer cells use B but most of them are just U.

I was recently at an IHO meeting to discuss S-100 which is the chart standard currently being designed to replace S-57. One topic was a consideration of ways to display the S-100 equivalent of this sort of data quality value. There was, as usual, much discussion on this, but to my amusement nobody pointed out that unless the chart producers actually encode this information then it does not really matter how it should be displayed. S-100 is a long way off but for now, please NOAA, could you start adding more zone of confidence information? It is really quite important information. The Nuno overview is useful in its own right and it displays the date of the source chart for each area. It also displays the data confidence level so if more of this were actually in the cells then we would really have an electronic equivalent of an SDD. Come on NOAA – we are all ready for you.

Traditional or simple?

ENC supports two types of symbology for buoys and beacons. These two symbol sets are referred to as ‘traditional’ and ‘simplified’.

Traditional symbols look a lot like those you would find on a paper chart. These are internationally agreed and some of them have been in existence for over a hundred years. So they are pretty familiar. They are used on all paper charts and as a consequence on all electronic raster charts. Excellent description of these symbols here.

Simplified symbols appear on ENC vector charts and were invented along with the ECDIS standard. Technically they are described in the S52 standard which dates from sometime prior to 1996 and is currently at edition 6.0 (March 2010). The DNC vector format also has a set of simplified symbols but these are different again.

In comparison the traditional symbols are more pictorial, more detailed and more descriptive than the simplified set. You might have guessed this from the name. An obvious question is why do these exist at all? The paper chart symbols are time server, proven, reliable and readily recognizable by anyone familiar with a chart. The simplified symbols are rendered (drawn on the screen) using just straight lines. This may have been easier to see on the coarse resolution monitors that were typical of 15 years ago.

Here are the symbols for a Lateral starboard hand conical  buoy with a Quick Green light.


Is one of these clearer than the other?

They both convey the same information so why invent a new standard? Actually this is a bit of a trick question because on a paper chart the buoy would be drawn solid black indicating it was green or black. ENC does not use filled symbols so the term ‘traditional’ needs to treated somewhat liberally. Why no fills? I am not sure but I would guess that the reasoning is that it might obscure something important underneath. So why doesn’t this happen on paper charts? Probably because the cartographer (chart compiler) makes sure that everything is drawn just so. It is hard for a computer to be suitably discriminating.


There are 58 traditional symbols but only 38 simplified ones.

So something has to go.

Here is a Pillar buoy with a ball on top. Long flashing white light. The Ball indicates safe water.

The traditional symbol shows you what the buoy looks like. It is a pillar with a ball on top. The simplified symbol just uses a red circle to indicate safe water. Maybe with an electronic chart you also have good positioning and so you are less concerned with visually identifying the actual buoy and more interested in that you are in safe water? Of course you can always inspect the properties of the buoy to find out what shape it is. Whatever the reasoning is I find it is not clear cut and certainly not an obvious justification for learning an additional set of symbols. You are going to need to know the paper chart symbols even if you prefer simplified on your ECS.

So which symbol set is best and why?

It seems to me that if you choose to use the simplified symbols then there should be a clear cut reason as to why they are better. The traditional symbols are familiar. Paper charts are not about to go away. Using a different symbol set means more learning and more chances to get it wrong. Why are there two symbol sets? Most ECDIS/ECS allow a choice for the display. Surely one of these sets is better than the other and that should be the end of it.

So what do you think? I’d really like to hear some opinion as to which you prefer to use and why. Does one set stand out better than the other? The simplified symbols use blocks of color which do not normally appear on a paper charts. So they certainly look different but is that necessarily an improvement? Were the originators of vector charts just showing off? The data is carefully set up so that information about an object and the way an object is drawn are quite separate. If you were so inclined you could create a whole different set of symbols and render the same chart data quite differently. Maybe this feature was so ‘clever’ that they just could not resist using it for something. What do you reckon?



The Nuno Software License

In a previous blog I was encouraging people to pay attention to what the software license actually meant. I shall now attempt to take my own medicine by describing the Nuno license sufficiently succinctly that you won’t doze off or lose the will to live before you get to the end.

On the way I may even convince you that this is a really good deal with no subtle clauses that are going to disappoint you.

Here is the small print – in headlines.


For an initial outlay of $100 you can have a license for a state of the art navigation system and a one year subscription to full support and update services. After a year you can choose to renew your subscription for a further $50.

If you want to know more; keep reading.

How to buy Nuno

On the Nuno website you create an account and pay for Nuno with your credit card. This gets you a license to use Nuno and a subscription for a year.

How to get Nuno and Install it

You may have already downloaded Nuno to try it out before you bought it. If not you can download it now. This will be the very latest version. As soon as Nuno starts up on your computer it will ask you for your account logon credentials. This is the same email address and password you used to create your account. Nuno will use these to activate over the Internet. Once activated Nuno is fully functional.

You can have Nuno installed and activated on two computers at the same time. This is so that you can have one PC for route planning and another, maybe a laptop, for use at sea.

You are now up and running with the latest version of Nuno and a complete set of up to date charts from NOAA.

During the next year

The subscription is valid for a year and entitles you to the following:

· You will be able to use our chart updating service. This is basically just one click to update all your NOAA charts.

· You will be notified of any updates to Nuno.

· Occasionally we find bugs or problems in the code. More often we want to roll out a bunch of usability and implementation improvements. You will be able to download, install and use the new version of Nuno with these fixes and improvements.

· In the next year we are planning to add several new features including Active Captain Integration, AIS support, S63 (commercial, encrypted ENC), auto-helm and a rolling road (whatever that is). You will be able to download, install and use the new versions of Nuno with these new features.

· If you encounter any problems or have any issues you will be able to contact us directly and probably have your question answered by one of the programming team.

After a year

The subscription expires in a year.

At the end of the year we will invite you to renew your subscription. This will cost just $50. If you renew your subscription then you can carry on with all the good things I have just described for another year.

Expired subscription

You can still use Nuno. It is yours to keep and use whenever you want.

If you ever lose your copy of Nuno you will be able to log into your account and download a fresh copy.

You can still update your charts but not via the update service. You will need to download updates directly from NOAA and then install them manually.

You will not be able to upgrade Nuno. Activation will be frozen at the latest version on the date that your subscription expired.

It is all on the chart but it is too much

Here are a couple of thoughts:

1. Most National Hydrographic Offices, and hence the government behind them, make some sort of assurance or even guarantee about the quality of their charts.

2. Electronic (ENC) charts are generally considered to be an improvement over paper charts. It is easier to be more accurate in using them and updating them for example.

Putting these two assertions together you might be tempted to think that the governments can now make and even stronger statement as to the reliability of their chart data. However scratch under the surface a little bit and this notion can come unstuck.

There are some fundamental differences between paper and vector charts; here I am just going to focus on display options. Paper charts don’t really have any, vector charts have lots. With a traditional paper chart the choice as to exactly what goes onto the chart and how it is displayed is determined by a cartographer (chart compiler). So when the chart is published it can come with as assurance about the accuracy of the data and (this is the important point so pay attention) exactly what the chart looks like. Two skippers in completely different vessels with totally different equipment will be looking at exactly the same image.

With ENC charts, the data will be just as accurate but control over the image has been diluted. If we were to compare several different types of chart viewer using the same data, showing the same area at the same scale then chances are that they would show a different image. Sure they would all be similar but sometimes the devil really is in the detail. In fact (I can already hear the pedants) if you were to try and match the display settings on each of these units them you would still find that there were some differences between the images.

The starting point of this problem is that there is too much data to display. There are some 180 different classes of symbol which are arranged into groups. 20 of these groups must always be displayed and 90 are optional. Of the optional groups 51 are normally visible, switched on and the remaining 39 are usually switched off. Ok – so if you are worried about switching something off that you should really be displaying then you might consider simply switching everything on. Here is what it looks like:

NY approach

On the left is the paper chart and on the right that nasty mess is all the ENC data. These two charts are intended to tell you the same thing so clearly this is sub-optimal. There is too much clutter on the vector display – something will have to go. In fact clutter is possibly the biggest problem with ENC data. So, you need to switch some stuff off – but what? Actually doesn’t it strike you as odd that right out of the box this chart is virtually unusable and so things have to be switched off? When are these things ever going to be switched on and why? How are you going to decide what should be on or off? This is the crunch; there is no easy way. I guess you could read a manual, learn about S52 viewing groups, brush up on cartography and give it a stab but that is actually quite a tall order. It is quite a lot to expect of your average mariner before they can use and electronic chart. It is also a moving target. You may well get the display looking just so but as soon as you start changing scales it can all go a bit pear shaped and if you use charts from a different producer then all bets are off. With paper charts you need to learn what they mean, with ENC you need to first decide what they should look like.

In all probability what you are really going to do is to take some reasonable default values. Fiddle with anything that you can understand and stop once you have a half decent display. This is a quite rational approach and this is one reason why all the ENC displays mentioned above are going to look different. There are many other reasons and these can rapidly get very technical but I hope you are getting the gist of this now. So the chart data may all be reliably accurate in line with the assurances of the Hydrographic Office but that is not going to help if the thing you just hit was not being displayed on the chart.

With Nuno we have taken the fairly pragmatic approach that the skipper is more likely to be interested in the chart as a navigation aid rather than a computer game. To this end we have attempted, to the best of our ten years’ experience in messing with ENC data, to make the chart display just work. There is a lot of clever stuff involving dynamic positioning of symbols, subtle re-scaling, jiggling labels around, changing fonts, adjusting for display scale, merging multiple cells and so on. The end result is a half decent chart display with very little messing around. It is all on the chart, well apart from one switch which we have termed anchoring mode. This enables additional data to be displayed in a way that would be appropriate if you were looking for somewhere to tie up. So this switches sounding, bottom type and some other stuff on. This is a feature in the new version of Nuno and it is coming very soon now.

NY approach 2

Selling software by the pound

You might think, quite reasonably, that since you’ve been to the store, handed over some hard earned money and come home with a nice new plastic wrapped box, that you had just bought some software. It says software on the outside. It contains a disc with the software on it. It is on my desk. It is mine. I bought it.

Nope you are wrong.

What you actually bought is a license. Even though you physically have the disc in your hand what you really have is a license and a copy of the software which you are only allowed to use according to the terms of the license. You did read the small print before parting with those bills I hope.

I guess the nearest thing to actually owning software might be owning the IPR in the source code but even that is often not clear cut. Several parties may have contributed. In fact this is quite commonly the case especially for any larger system. It can get very messy, very expensive and if all you want to do is use the software then it is probably very little use. You really don’t actually want to own the software – you just want to be able to use it whenever you want – kind of like owning it.

Let’s get back to the store. The crux of all of this is not legal ownership so much as allowing you to do what you want to do with the thing you have paid for. So you buy a license which lets you take it home and use it. Feels a bit like I bought it and there doesn’t seem to be much practical difference so is that the end of it?

Well no – I wouldn’t be blogging about it if it were that simple (ok - I might, but in this case I’m not).

Software is very different to most things you buy. By comparison to, say, a puppy dog, it makes less poo (usually), it does not age and it is easy to copy. In some ways it is a bit like music and shares some of the music problems:


If I buy this CD can I use it in all my CD players?

Yes, of course (^_^)


Can I rip it and copy it to all my MP3 devices?

Errr… not so sure (-_-)


Can I copy it to all my friends and use it for my vids?

Try that we’ll be round to shoot the puppy (>_<)


Actually software has even more problems. If your favorite singer hits a bum note then you might not expect to get an upgrade to the album with it fixed (although this can actually happen). However you would, quite righteously, expect buggy software to be fixed (although this often doesn’t happen). Then there is all the business about upgrades and new features. What about support when you can’t work out how to use it? Finally there is the service aspect. Most modern software comes with some sort of internet based functionality whereby information is provided as a service. So how do you make a license for this lot? Well there are many ways and this is where it starts to get difficult – not just for you but for the company making the software as well. I did really mean it earlier about the small print. You haven’t bought the software so what on earth have you bought?

What does a license cover?

Here are some commonly occurring elements in software licenses:

Use of the software.

This is a fairly simple consideration and also the most important so it is what is usually focused on. These conditions will usually apply to a specific version of the software.

· The software can be used for a limited time. Often called a subscription.

· The software can be used indefinitely.


What is going to happen when (not ‘if’) bugs are found in the code? There are several common approaches including:

· Unlucky – learn to live with it.

· A fix will be released for this version. This may only be made available to people who bought it recently or who have paid extra.

· This will be fixed in the next version which also includes new cool features so we are going to charge for it.


It is not guaranteed but most software will continue to develop after the initial release. So what does the license say about upgrades?

· No such thing. Each new release is treated as a brand new software product.

· Ok, there is such a thing as an upgrade so we will charge a reduced price to existing customers.

· It is version specific. So the girlfriend 2.0 license might allow upgrades to girlfriend 2.1 but not to girlfriend 3.0 (with the impressive new features).

· Unlimited. The license allows all upgrades to the software as they become available.


You cannot make the tachyon emitter operate at full power and you have no idea whether to reverse polarize the matter stream. How can you get some help? Just what is actually meant by support covers a wide range of notions. Here are a few:

· None. Just Google it if you have an issue.

· Some information on a website. Bit static but you may find something useful if you are lucky.

· A forum, chat room or notice board. Bit more interactive but can have a poor signal to noise ratio. Useful to chat in a more general sense but less good if you have a specific problem which is stopping you working.

· Support by phone or email for a limited period of time. This is another type of subscription but it is actual real support though – you can ask a direct question and get a response. Might not be a very good one but that’s not the point since we are looking at license models.

· Pay per use support. There are various ways to extract your money such as a premium rate line or a requiring a credit card. This type of support can lead to lovely scenarios where you end up paying a company to tell them that there is a bug in their software.


This is often associated with some of the provisions above so for example software upgrades and support issues may be dealt with through a website that you need to log on to and this is part of the subscription.

Sometimes the service maybe for the provision of data, such as a global database of puppy names and what they mean.

· Always available. If you can run the software you can access the service.

· Part of the subscription. You can access the service while ever the subscription is up to date.

· Pay as you go. You pay for what you use when you use it.


So here is the quick and easy checklist for a software license. Go on… have a look at the small print. This is what really defines what you are buying - not the picture on the box.


How long can you use the software for? Image0009

How many computers can you install it on? 

Are there any other restrictions on use?


What is the provision for patches?

How long are patches going to be available?

How do you report a bug?


What upgrades are likely to be available for this version?

Support and Service

How much can I get before I have to start paying?

Transmittals, exchange sets and loose cells #2

The last post dealt with loose cells. Now we are going to consider Exchange Sets and finally Transmittals.

The Navigation software needs to import cells and updates. The result of this is stored in some kind of SENC. That is a System Electronic Navigation Chart (Google for SENC and you’ll find many definitions other than this one but just bear with me). The thing is that while a single .000 file can be displayed directly the cell update files need to be applied to the corresponding base file first. They also need to be applied in order. The SENC then is the result of installing base files, update files and possibly other files. The SENC is what your navigation system reads to display charts. An Exchange Set is the standards definition of the set of files that can be applied to a SENC.

The ENC product specification states that an exchange set contains a catalog file, one or more data files maybe a readme file and possibly some text and picture files. These last two are referred to as auxiliary files and contain information which is supplementary to the cells. That is, an object in a cell may refer to one or more auxiliary files to provide addition information.

The catalog file contains an entry for every other file in the exchange set. It describes where the file is in the exchange set (different organizations may use different folder structures) and also some checksums to ensure that none of the files are damaged. Bearing in mind the previous discussion about updating cells you might also hope that it contained the edition and update number of the cell files in the exchange set but sadly this is not the case. Some organizations put this information in a comment field but since this is not mandated it is not reliably present. So you can have update logic that uses the edition and update numbers from the catalog but it also needs to be able to fall back to reading this information from the cells themselves – which is perfectly possible but takes longer.

The standard describes how the volume label of the exchange set should be made up. If you are not savvy about volume labels then no matter because nobody really takes much notice of this. In principle an exchange set could be split across several volumes but I don’t think this ever happens. In the volume is a folder called ENC_ROOT which contains the catalog. The cell files may be in this folder or are commonly placed in sub-folders. A directory listing might look like this:


Does that bring back memories of those heady DOS days c:\ > ?

So the basic update algorithm is to locate ENC_ROOT\CATALOG.031, read it and then install all the files it mentions. Overall the mechanism is a bit clunky and can lead to some seriously cryptic error messages. It can be made to work but there are corners which have not been thought out very well. Management of the auxiliary files is one example of this. In fact some of the omissions are possibly evidence that the standard preceded any real implementation.

A Transmittal is a super set of an Exchange Set. Each producer of data tends to have their own take on the standard and often include additional files. This is allowed by the standard. The trouble is that if any software relies on the additional data then it can only be used with data from that supplier. This is a pity because some of the additional information can be quite useful. There is often a complete catalog of what is available (albeit just from that producer) and other information. Check for a folder called \INFO or the such.

The standard actually prohibits the use of compression (S57 Appendix B1 5.2 if you care) which seems a bit unfair. NOAA go ahead and compress it anyhow so when you download charts from http://www.nauticalcharts.noaa.gov/ they will arrive in a zip file. Decompress this and you will find the transmittal contains an exchange set pretty much as above. Each cell has its own folder which contains the base cell and sometimes quite a lot of updates. The readme file contains a catalog which is not in the most readable form but can still be quite useful.


The catalog information in a transmittal can make for a useful geographical display.