TCP Connection Problems on Apple iOS 10


Since Apple’s release of iOS 10 for iPhones and iPads, we have been getting a number of calls and emails saying that various navigational Apps that read wireless NMEA data from our products have stopped working, including our free iAIS app.

There are two modes/protocols that our wireless NMEA products can work in; TCP which is a reliable one to one type connection supported by most apps and UDP which is a broadcast protocol that allows multiple devices to all receive the same data.

When we started to investigate, we found that TCP communication on all Apps no longer worked with iOS 10 and UDP only worked on some apps. At first we thought this might have been an Apple API type change that had caused the problem, but then we discovered that changing the IP address of our wireless NMEA products from to fixed the problem.

The IP address range is usually reserved for Ad-Hoc networks where there is no DHCP server and dates back to our first iAIS product (released in 2011) that only supported Ad-Hoc networks. With the release of Android, which did not support Ad-Hoc networks, we updated our wireless NMEA products to the more common Access Point mode but retained the IP address, to avoid changing too many Apps and Documentation.

Now it seems that Apple are clamping down on TCP connections on Ad-Hoc networks and this means that all customers who have updated their iPhone or iPad to iOS 10, will need to change the IP address of their wireless NMEA product, if they have one of our; iAIS, WLN10, WLN10HS, WLN20, NavLink, PilotLink or AIT3000 units. Please note that our iNavHub and Sonar Server products are not affected by the iOS change.

To make this procedure as easy and simple as possible, we have created a new Tech Note that explains what needs to be done. Click here to download.


Wi-Fi Congestion


The range of 2.4GHz frequencies reserved for Wi-Fi is fairly limited and with so many Wi-Fi devices and networks these days, it is not unusual for wireless networks in the same location to share the same frequencies and this results in lower connection speeds and even connection drop outs in extreme situations.

The good news is that the wireless network(s) on your boat, once out at sea, will not be affected by the wireless networks on land or on other boats. That said, these days it is not unusual for larger yachts and powerboats to have two or more wireless networks and so it is really important to ensure that your own wireless networks are working at peak performance and not sharing the same frequencies.

The good news is that most Wireless Routers and Access Points can be configured to work on a specific frequency and so you should be able to ensure that each network is using its own frequency band without any overlaps.

There are affectively 13 frequencies in the 2.4GHz range and each wireless router will use five adjoining frequencies to setup its network. Looking at the diagram above, where each coloured curve is a separate wireless router/network, you can see that in general three frequencies are used; 1, 6 and 11. which allows three routers to work side by side with no overlapping/sharing of frequencies.

So how do you optimise the frequencies used by your wireless networks ? Well first you need to “see” what is going on by carrying out a wireless survey of your boat. This can be done using a number of free programs and apps. Unfortunately Apple do not allow iPhones and iPads to provide this level of Wi-Fi Information so you will need to use a Windows PC or Android device to do your wireless survey.

If you have an Android phone or tablet, then you are in luck as the free App “Wi-Fi Analyzer” is one of the best tools available and created the image above. For Windows PC users then “NetSurveyor” is very good or “WiFiInfoView” which is not so graphical but is only a few hundred Kilobytes in size and needs no installation, so can run straight from your memory stick.

Whichever tool you use, once you have conducted your wireless survey, you will be able to see what frequencies your wireless networks are operating on and decide if you need to change them. All Digital Yacht wireless products can be changed to use a different frequency and should you need to do this, please contact us for instructions.

Testing Wireless NMEA Data

iAIS TCP-IP Screen


With more and more wireless NMEA systems being installed on-board boats, it is very useful for dealers, installers and enthusiastic end users to have simple tools to “view” this wireless NMEA data.

Traditionally, wired NMEA0183 data was viewed using an NMEA to USB cable connected to a PC and then a program such as Hyperterminal (included with Windows up to WinXP) would be used to display the data. In fact Digital Yacht released a free, dedicated NMEA Display program to use on Windows Vista/7/8 and this proved to be a popular tool for testing wired NMEA0183 systems.

With wireless NMEA systems it is much easier to test using a smart phone or tablet and we would recommend the following free apps;

For Apple iOS Devices – our own free iAIS app (see image above) has a very simple raw data view window that can be used to display the wireless NMEA data in TCP or UDP mode. Alternatively iNMEA Logger is another free app, written by the company that developed the popular iRegatta App that can log 30 seconds of received data and create a text file of the results, useful if you do not understand NMEA0183 and want to send it to someone who does.

For Android Devices – there are no specific wireless NMEA Apps, but there are a lot of terminal programs that display TCP and UDP data and after trawling through a fair number of apps, we came across TCP/UDP Terminal App which we think is the best Android App found so far.

Once you have installed your app for displaying wireless NMEA data, then you need to know what you are looking at. To buy the NMEA0183 Specification costs quite a lot of money but there is quite a lot of data on-line, you just need to hunt it out.

Unfortunately a lot of the information on-line is quite old and some of the newer sentences are not fully explained. The NMEA do in fact publish a complete list of all Sentence Identifiers with a short description of what they are (not the complete sentence description) and this list also includes the proprietary Manufacturer’s ID – these sentences start $Pxxx, where xxx = the manufacturer identifier.

It should be noted that most wireless NMEA data is “human readable” (ASCII Text) but the AIS sentences VDM and VDO have what is called a “binary encapsulated” section (bit like a zip file) to reduce the sentence length – see example below.


This means that you will not be able to make sense of the AIS target information in the VDM and VDO messages, but our free iAIS app does display this information on the main plotter screen, so worth having a copy of this app.

iNavX featured in Apple Developers presentation

photo 2


Tuning in to the live stream from yesterday’s Apple Developers Conference (WWDC), we were pleasantly surprised to see iNavX being used on a yacht in one of the presentation videos. It is not often that marine products are part of such a high profile event and it was great to see an app that we know so well, get worldwide visibility in the Apple video.

The video showed lots of people and the apps they use and at around 1min 40secs in Emily Penn appears and tells us how she uses iNavX aboard her yacht as part of the work she does with Pangaea Exploration

photo 4

The video was very well put together (it was Apple after all) and anyone that missed it can watch it again by clicking here but you will need Quick Time installed to view it.

It was fitting that iNavX was featured in this video as it was the first marine app to appear on the Apple Store and has continued to be one of the most popular marine navigation apps. Using Navionics charts, it provides a number of advanced features above and beyond what the hugely popular Navionics App does, including full support for wireless NMEA, instrument displays and a very good AIS implementation with CPA and TCPA alarms.

For anyone wanting to do serious chart plotting and navigation on their iPad or iPhone, iNavX is well worth considering and coupled with our wireless NMEA products such as the WLN10HS, NavLink or iAIS, it really does make iPad boat navigation a reality. For more information download our White Paper guide here iPad Navigation Afloat – a Digital Yacht White Paper

Adding our iAIS to a Garmin 4000-5000 system

Garmin 4000-5000


Earlier this week, we were giving some advice to a customer who wanted to add an AIS receiver to his Garmin 4008 chart plotter and at the same time go wireless and get GPS and AIS data to his iPad.

The Garmin 4000 and 5000 series chart plotters were very popular and powerful units and although there are now newer Garmin Chart Plotters available, there are a lot of people who use these units and who may also be considering adding an AIS or going wireless.

With NMEA2000, four NMEA0183 inputs and two NMEA0183 outputs there are plenty of interfacing options on these Garmin units, but to keep things simple we suggested using our iAIS receiver (with built-in wireless NMEA server) to both provide AIS data to the Garmin 4008 via one of the NMEA0183 inputs and send the same data wirelessly to the iPad.

To ensure the best possible GPS reception, where ever the iPad was used and to allow the Garmin instrument data (speed, depth, wind, etc.) to be repeated on the iPad, we also suggested taking an NMEA0183 Output from the Garmin 4008 back to the iAIS which would then combine this GPS and Instrument data with its own AIS data and send everything wirelessly to the iPad.

One of the NMEA0183 ports on the Garmin 4008 was already being used to provide position data to a DSC VHF radio so we used the output of Port 2 to send the GPS and Instrument data to the iAIS and then connected the iAIS output to the Input of Port 4 on the Garmin 4008 – click on the diagram below to see the exact wiring.

Garmin 4000-5000 Series to iAIS

The only menu setting that we had to change on the Garmin 4008, was to set Port 4 to the High Speed NMEA baud rate of 38400 and everything was good to go.

It the Garmin had already been connected to another make of AIS or the customer had wanted to fit a transponder, then one of our WLN10HS units could have been added to the second NMEA0183 Output to go wireless or alternatively one of our NavLink units could have been connected to the NMEA2000 network.

With wireless NMEA data now available on his iPad, it was just a case for this customer of choosing one of the many Navigation Apps that are available for the iPad and he could start to use his iPad as a full function chart plotter. Click here to see our previous post on iOS Apps.

Using an iPad for marine navigation – a Digital Yacht white paper

We’re all familiar with dedicated electronic chart plotters for navigation afloat.  Since the introduction of GPS about 25 years ago, dedicated marine plotters have become the back bone of modern electronic navigation systems.  But whilst smaller 4 and 5” plotters have tumbled in price, larger 8-15” devices remain stubbornly expensive.  The cost of the electronic cartography can also be high and you’ll often be hooked into a closed or proprietary “eco” system for accessories, upgrades or extra features.

Consumer devices like the iPad do offer an alternative and with iPad sales now over 270 million units to date, they bring an economy of scale but also, importantly, a network of software developers making niche apps – many of which can be useful for marine utilisation.

navlink key screen shot landscape

The core iPad hardware revolves around a high resolution 7.9” or 9.7” touch screen display.  With screen resolutions now at 2048 x 1536 pixels for the latest iPad Air, it outpaces dedicated products by a mile yet costs under £400 including vat – even cheaper if you’re in the US.   They also feature wireless interfaces to allow integration with other on board devices and systems and with internet connectivity can bring a host of “cloud” data to your boat – from the latest weather reports to charts updates or crowd sourced data.

Whilst an iPad isn’t waterproof, there’s a variety of protective cases now available and of course 12v chargers, adaptors and mounting options.  Sunlight viewing can also be challenging in very bright conditions but this document outlines some good solutions to this problem.

At Digital Yacht, we firmly believe there’s a place for consumer devices integrated into a boat’s system and we have a wide range of wireless hardware and applications that make this a reality.  We’re determined to offer better value in boating and electronic navigation, safety, communication and entertainment afloat and the iPad revolution is a big step forward here.  Download our latest White Paper (June 2015) guide here iPad Navigation Afloat – a Digital Yacht White Paper

Connecting a Garmin 400 or 500 Series Plotter to iAIS

iAIS Wireless AIS with iPad+Garmin

The Garmin 400 and 500 series plotters are some of the most popular small boat chart plotters on the market and it is not surprising that we get many enquiries about how to connect our products to them. Normally customers just want to add an AIS receiver or transponder to their Garmin unit, but last week we had an interesting enquiry from a customer that wanted to add AIS, but also wanted a wireless solution for his iPad.

This particular customer only wanted to receive AIS targets and so our iAIS was the obvious choice but had he wanted a transponder then we could have done a similar setup with one of our AIT2000 and WLN10HS units. As we were discussing how the two systems would wire together, I realised that with the two NMEA 0183 ports that the Garmin has and the NMEA 0183 input (4800 baud) that our iAIS has, that we could also have GPS data and other NMEA data from the Garmin transmitted wirelessly to the iPad with the AIS data.

The benefits of this arrangement, are that any iPod Touch, iPhone or iPad can receive AIS and GPS data anywhere on the boat, even if they do not have their own internal GPS, such as the Wi-Fi only iPad and iPod Touch. Even 3G iPads and iPhones that have their own internal GPS, will benefit from the always on, Garmin GPS which should be more accurate, particularly when you take your iPad/iPhone below deck.

Of course a suitable App will be required to read the AIS and GPS data, but with some recent new app releases, the number of available Navigation Apps that support wireless NMEA are growing. This particular customer intended to use the popular iNavX app, but other apps worth considering are; iSailor from Transas, iRegatta from Let’s Create, the new Imray app or the SailTimer app that I recently wrote about.

The customer was delighted with the proposed solution and I quickly drew up the following connection diagram and sent it to him. I hope that by publishing this article, many other Garmin 400 and 500 series owners might benefit from a new wireless AIS solution.

iAIS to Garmin 400-500