Replace GPS with Tablet + software

[barnakiel]

Originally Posted by Visarend

IMHO redudancy is the way to go. I still keep a rather old BW plotter with CMAPS, along with a pc running Linux and OpenCPN, and a rugged waterproof BlackView 9500 P phone with the largest battery (10,000) giving almiost a week in standby, running OpenCpn and Navionics. Oh,and I still keep all the paper charts.

Exactly. I have the same mantra.


Cheers,

barnakiel

[alanrothenbush]

I bought a Panasonic "Toughbook" tablet (the Windows version) with daylight readable screen. It's at least as readable as my dedicated chartplotter, which I retained.

I then installed Android X86 instead of Windows 10 and followed that up by installing Navionics, which I quite like.

(I didn't buy the Android version of the tablet because it's smaller than the Windows version, not quite as bright and mostly, because the price was right on the Windows version.)

This tablet does not have built-in GPS (although some variations do), but that was easily solved, now that Navionics allows you to connect NMEA devices via WiFi. I simply built a small NMEA to WiFi device (10 bucks), connected it to the chartplotter output and I get everything I need sent to the tablet wirelessly.


Alan

[daveNZ]

Originally Posted by alanrothenbush

...............I simply built a small NMEA to WiFi device (10 bucks), connected it to the chartplotter output and I get everything I need sent to the tablet wirelessly.


Alan

Is it possible to describe how, in brief??
Or should I just buy a Yacht Devices or NMEA Tools product?
I would love to use this for the Autopilot feature in iSailor to a Raymarine autohelm. (Which would need to be bidirectional)

[barnakiel]

Yes. It is as Alan said.


All you need is an old wifi router. Google some.


I walked by a local salvation shop they have two on the shelf. EUR 2,00.


I am likely using the same software Alan does. My explanations is somewhere up the thread too.


It is not all that likely that iSailor is capable of sending any nmea data via wifi though. And why send it via wifi is another story while you can simply walk up to AP faceplate and push the button.


b.

[daveNZ]

Originally Posted by barnakiel

Yes. It is as Alan said.


All you need is an old wifi router. Google some.


I walked by a local salvation shop they have two on the shelf. EUR 2,00.


I am likely using the same software Alan does. My explanations is somewhere up the thread too.


It is not all that likely that iSailor is capable of sending any nmea data via wifi though. And why send it via wifi is another story while you can simply walk up to AP faceplate and push the button.


b.

Isailor can send nmea autopilot commands, (as well as receive).
Also a wifi router won’t convert NMEA 0183 to/from wifi, so not sure that helps. I don’t want to use a laptop in this either.

[barnakiel]

Originally Posted by daveNZ

Isailor can send nmea autopilot commands, (as well as receive).
Also a wifi router won’t convert NMEA 0183 to/from wifi, so not sure that helps. I don’t want to use a laptop in this either.

Of course iSailor can or cannot create such commands NOW MY QUESTION was can it deliver (send) these commands over wifi? Because if it cannot, the router will never be able to forward the commands to the AP. If iSailor can deliver nmea commands via wifi, a wifi router can forward these commands to any wired or wireless device in the network.



How else do you want iSailor to talk to a wireless device (a router)? Thru a wire? If YES, then your AP must be able to receive wireless commands. But I think few do. Correct me here.



YES? NO? MAKE A DRAWING?


The router does not do any 'converting'. The router gets the command (over wire or over wifi) then forwards this command to where you want it. Thru a wire (LAN cable, RS cable) or wirelessly.



If your iSailor thing does NOT send the AP command over wifi, how can such a command reach a wifi router???


Standby,
b.

[alanrothenbush]

Originally Posted by daveNZ

Is it possible to describe how, in brief??
Or should I just buy a Yacht Devices or NMEA Tools product?
I would love to use this for the Autopilot feature in iSailor to a Raymarine autohelm. (Which would need to be bidirectional)

Three questions, I'll provide three answers, only the first being lengthy,

1. My part is a little device with a microcontroller and Wifi on a circuit board, about 1" x 1", including antenna, known as an ESP8266. It has about a dozen connections to the physical world, including serial connections that match the serial output of a typical chartplotter (which is to say, that does not match the serial connections to a computer.)

To digress a bit, I am, quite frankly, astonished at what a couple of bucks can buy today. I clearly remember the day when WiFi was expensive, and only the very fanciest of notebooks had it. And the microcontroller, well, the CPU and RAM in this thing roughly match that of a 10 year old computer once worth piles of money.

Anyway, I wrote a tiny bit of code to "listen" to NMEA position and depth data coming in the serial port and blindly send that raw data via WiFi to any device that's listening.

I then configured Navionics to "listen" for that dumb device and tada, there's my numbers.

Now, I understand that Navionics will "listen" for a number of devices from quite a number of manufacturers. However, as near as I can tell, most all of these devices do not send plain, raw NMEA data out. It seems as if they all encapsulate the data in some undocumented, proprietary manner.

Maybe they do this to protect their own financial interests or maybe there's some valid double-checking going on that I'll discover at the worst possible moment (isn't that always when bad things happen?), I really can't say.

What I can say is that all I wanted was a way to send GPS and depth data to my tablet, and when I got that, I didn't pursue it further. My tablet is just a convenient tertiary device, my secondary device being a decent chartplotter and my primary device being paper (cardboard) charts.

I say "cardboard" because while I have all the official paper charts a man could ever want and update them religiously, I tend to print (from OpenCPN) letter sized versions on card stock of a particular route at various zooms, marking them up by hand as appropriate and sticking them in plastic sleeves.

So, for my very narrow use case, there's no need to spend more on a fancier commercial unit. However, if I wanted more data to appear, I think I'd need to buy something else, as Navionics appears to only accept these two pieces of info from this type of device.

2. Should you buy something else? From your question three, it seems as if you might need to. However, even if your needs precisely matched mine, you might want to. Remember, a failure in my $2.00 unit is at best an annoyance; I have other, perhaps better ways to navigate. If your computer/tablet is the only way for you to find your way home, you might want to spend some extra bucks.

3a. I don't know if this scheme would work with iSailor; never tried it.

3b. Even if it does work with iSailor, it's not currently bidirectional. It could (maybe even fairly easily) be made bidirectional, but it's not now.

3c. Even if it was bidirectional, or I made it so, I would not trust it for autopilot use.

The reason for this is a geeky technical point; I send the data using a protocol known as UDP.

Most networking that people are familiar with uses a protocol known as TCP. TCP ensures that data gets from A to B, uncorrupted and in the right order, with the sender knowing that the receiver got it, retrying (and retrying and retrying ...) until the receiver does acknowledge receipt.

UDP is dumb. The data leaves (via wire or Wifi, it matters not) and the sender neither knows nor cares if someone on the other side ever got it. As such, UDP is simple and easy to implement. And in this case, it's entirely appropriate. The data appears from the chartplotter about once a second, and if a packet gets lost here or there, who cares. How far do we travel in a second .. how much does the depth change in a second?

But to lose a bit of autopilot data, with the tablet never knowing that the autopilot didn't get it, or to have the command corrupted ...

Note that I've been in the computer and electronics industry for 50 years and I'm suspicious of wires for autopilot use. Wifi to steer my boat? Tough for me to get my head around that.


Hope this helps.


Alan

[s/v Jedi]

iSailor controlling the autopilot works like a dream. You can even control it from an iWatch.

I recommend a good, rather powerful dual-band wifi router and have your NMEA-wifi converter connect to that, either by Ethernet or as a wifi client. Good converters from Yacht Devices and the Vesper AIS units can do this.

Those converters can also operate as a wifi router themselves but I find their signal level a bit weak for use around the boat.

@Barnakiel iSailor is glorious with the autopilot. It can steer for a goto waypoint or a route and also has a dodge mode which works great. iSailor sends all required NMEA command back over TCP the same address and port as it is receiving NMEA from. The converter puts that back on the NMEA 2000 network and the converter becomes the navigation source used by the autopilot

There are $10 RS-422 to Ethernet converters that can be connected to NMEA0183 ports to do this but even at hi speed 38k4 those ports can not carry all data if that includes 10Hz heading and AIS.

[s/v Jedi]

Here’s a screendump showing AP controls and another while active. I swiped to depth to see the drop-off in which case iSailor puts a mini control in the upper left corner

[barnakiel]

OK, so Dave has his answers.


Cheers,
b.

[daveNZ]

Thanks for the long answers Alan. I’m(was) a computer scientist but no real electronics ability. So I could build to a plan but will probably buy. I’ll be interested to read about the micro controller though. Appreciate the response.

S/V Jedi, thanks for the comments and screenshots, I hadn’t seen the depth module before!

Barnakiel, not sure if I caused some angst here?? I knew isailor could output NMEA over wifi, which then needed to be converted to RS422 for the AP. Just was interested in the DIY approach Alan had succeeded with.
Thanks all.

[barnakiel]

Originally Posted by daveNZ

Thanks for the long answers Alan. I’m(was) a computer scientist but no real electronics ability. So I could build to a plan but will probably buy. I’ll be interested to read about the micro controller though. Appreciate the response.

S/V Jedi, thanks for the comments and screenshots, I hadn’t seen the depth module before!

Barnakiel, not sure if I caused some angst here?? I knew isailor could output NMEA over wifi, which then needed to be converted to RS422 for the AP. Just was interested in the DIY approach Alan had succeeded with.
Thanks all.

Dave:


Good lord save me, no angst at any point. If I did sound rough at edges PLS lay it on my non native and textbook based English! The practical part came for me in a loft at Westhaven where as you can imagine English was not particularly close to Queen's English.


Sorry for causing any bad taste - to wash it off, I invite you to a beer at a fine Ponsonby bar, as soon as we revisit your lovely place! Deal?



Last night I actually dug into the details of how any plain old wifi router is converted to act as a nmea / wifi bridge device - wired or wireless. Free (mostly, if you solder).



The wired part goes to router's terminal pins (via a chip), to a USB port of the router, or to the LAN terminal.


The wireless part uses TCP or UDP protocols.


In my particular case, I use USB port on the wired side, and TCP method on the wireless side.



Here, the guy who built kplex explains all detail:
Kplex: An NMEA-0183 Multiplexer


Kplex uses OpenWRT environment:
https://openwrt.org/toh/start



So, to reiterate, my poor man's nmea wifi router is:


- any old router that can run OpenWRT software,- kplex package,


In my particular case, the wired part is done via the USB port (and a USB to RS cable) but only because this is what I had at hand.


In your boat, iSailor will send wifi nmea AP wpt to the router, then the router will output a wired RS (232or422) to your AP. The AP connection is again with a plain RS / USB converter cable. Just mind you get a router with USB port. (Alternatively you can use a chip and solder the AP cables to the terminal on the router).


Time to build and set up about one hour. Cost 0 to 10 USD (the converter cable cost 5, online)


Cheers,
barnakiel

[wingssail]

Following this thread I've been learning quite a lot about connectivity and networking on a yacht. I haven't seen the benefit of most of it over my rather simple system, but fair enough, you guys have done some neat things.

I am encouraged by the number of people who recognize the advantage of being able to create routes (passage planning) below deck at the nav station then display it topside while underway.

But I am surprised at the number of people who use Navionics mobil app and love it. Personally I find it's tools inadequate to do a seamanlike route using pre established waypoints, etc.

To confirm my previous impression I just chatted with a Navionics help deck person. I found the following which I think are quite disturbing.

• You cannot create route using previously saved Markers (waypoints) except as the beginning and end of the route.
• You cannot modify a marker's coordinates once it is created, not even by dragging.
• You can drag a waypoint in a route but you don't see the coordinates.

There is more, but to me these are disqualifying. What you are left with is the crude finger pointing on the chart to establish a waypoint and little way of changing it, and you cannot make new routes using old waypoints. It seems like a toy, not a good navigation tool. I prefer OpenCPN or some of the other high quality charting systems.

Honestly, if you are happy with Navionics as a tool then, not to be offensive or demeaning, but it tells me something about your level of sophistication when doing navigation.

[barnakiel]

Maybe, the choice of a specific App and how it is actually used (which functionality counts vs. which is a 'nice have') is something related to what cartography one prefers and then also by not willing to switch over from things we grew used to.


What I am saying is that we each use different functions of the same packages and we are also not very willing to search for "better" tools while the ones we have had for a time still work fine.


I have used or tested easily a dozen different Apps. Yet the one I like best never ever pops up in conversations. Why? Well, hard to say. But I can tell you that as soon as you mention anything else than Navionics or C-map (in any of its reincarnations) you virtually draw a blank. Half the stock uses A the other part of the crowd uses B. An outlier may have an OpenCPN or something else (like me: MapTech kit rebranded under NV Charts App).


And on the big boats I worked for, there were no Apps. We just had Ray or B&G on many plotters throughout, and that was that. No funky smartphone navigation allowed. As a side note, on the only boat that had two wireless mobile devices (Panasonic based with Deckman (?) software) I was advised 'not to use these in the cockpit' - price unit like 2k or something. The owner and his female visitors very aptly used these in their beds - to watch Netflix series (well, sorta, it was 2011, before Netflix).


Well, well. Long story short. All depends on what one has and what one got used to. A well known App with fewer functions may beat a more fancy newer solution that we do not have and one that we would have to learn.


Imho sophistication tells little about how good a navigator you are.



Cheers,
b.

[s/v Jedi]

So let me show how that works on iSailor; when you create a waypoint, it is just a symbol on the map, but you can enter/edit coordinates so you have 100% precision. On the first screendump you see the little red flags which are waypoints. Then there is the route: you can not add these waypoints to your route, but you can move them on top of them, or you can enter their names and coordinates instead of doing that for the waypoints. The reason I do it like this: the waypoints are the ones from the paper Explorer Charts for the Bahamas. But I don’t always follow them. In this case a megayacht was anchored right in the channel so I went around. I also do shortcuts etc. Then I can erase the route but keep these waypoints permanent.
In the 2nd screendump you see the attributes of route waypoints. I use the turn radius to have the autopilot make pretty turns allowing me to trim sails etc. It’s pretty spiff.

iSailor is based on the commercial Transas charts which is the main (Russian) competition for CMap.