Just getting down to final preparations for my trip to the Isles of Scilly and am installing a simple AIS receiver in order to avoid getting run down by super-tankers etc, in the fog, in the TSS off Lands End.
My chartplotter display is fairly small (Garmin GPSMAP 550s) so I'm planning to view AIS info on my iPad and iPhones, which are loaded with Imray charts and can communicate with the AIS receiver via wi-fi.
Obviously to make any use of the AIS data I need to be able to view it in relation to my current position hence I need GPS data on the iDevices.
The iPhone has GPS but the iPad is wi-fi only so it will only have some position data via a hot-spot generated by the iPhone; when it's getting a 3G signal.
I could, of course, get the GPS data from the chartplotter via NMEA but I want to be able to switch the chartplotter off when not needed to save the draw on the batteries.
To get a better idea of how the iPad worked I took it for a walk this afternoon to see whether it kept track of our whereabouts under differing conditions. Having lost my regular wi-fi connections I then turned on my iPhone's hotspot to check my assumption that the iPad could then follow me ok; which it did.
Next I switched off the hotspot on the iPhone AND wi-fi on the iPad. With wi-fi off on the iPad it couldn't follow me; as you would expect BUT with wi-fi on (even though NOT connected to any network) it then had no problem following me.
I guess my question really is: "how does the wi-fi only iPad follow me when not connected to a network"? Will this still work at sea?
If not, I suppose my best bet is to buy a cheap GPS tablet that will run my Imray chart and boat instrument software
Any thoughts? Should I just be happy with the iPhone?
MacGregor 26M 2009 - Sky's the Limit - Suzuki DF50
Anyway, having tried it out a little on the boat this morning it's obvious that, even if the iPad is able to make a rough guess of its position, it's nothing like accurate enough for navigation, especially the terrain avoidance type.
So the question is, should I get an iPad with GPS. The advantage of that would be that I needed rely on my chartplotter for its GPS data - even assuming I manage to port this via the AIS unit's wifi to the iPad.
I did try this today, which seemed reasonable given that I've already got a good known feed from the chartplotter to the VHF (for DSC). I simply added a parallel spur from the VHF to the AIS but no joy.
Quark-Elec, the AIS manufacturer say this is a normal problem as the Garmin plotter uses RS232 for NMEA0183 whereas the AIS unit uses RS422. They offer what they call a Garmin Bridge unit for £15.50 although some folk suggest that you can simply connect up in the I did (above).
Anyway as it didn't work for me I've ordered the Garmin Bridge and will take up the story when it's installed.
Sorry this story is a bit of a dog's breakfast but it really helps me to think it through.
And while I remember, I've found that by running the chartplotter with the screen at a low brightness level the current draw is significantly lower - will be specially useful at night when the solar panel is not producing.
Again, any thoughts welcome!
MacGregor 26M 2009 - Sky's the Limit - Suzuki DF50
Hi Mike
As you've discovered, the only system that gives navigation accuracy of position is GPS (ha! my auto-correct just tried to turn GPS into God, gives that sentence a whole new meaning ...).
So you need a device with a GPS receiver, you can't proxy that through a hotspot. The only protocol that can send GPS data between devices is NMEA, which is how a chart plotter can make use of an external receiver, but I've never heard of a standard tablet that talks NMEA.
If you want a tablet just to run your charts, there's quite a few on the market a lot cheaper than an iPad. Price largely depends on whether you want a 7" or 10" screen.
At the AGM, Dave Newton had a ruggedised one he got 2nd hand, he told me they're easily obtainable, but I don't know any details. Dave - can you tell us more about it?
Rick Jones (Treasurer), former 26X & 19 owner, Isle of Wight
Mike you are clearly far better at all this new fangled high tech stuff than I am, I gave up software 25 years ago. Now I prefer things I can hit with a hammer!
I have a Panasonic Toughbook, They are available for anything from £4K ish for the latest newest models down to <£100 for a secondhand ex-MOD one which only a few years ago cost the MOD £KKKK. They are a laptop with a flip over touch screen so you can use them as a tablet (more the size and weight Moses used) but they are bordering on indestructible. The army claim they will stop a bullet but I will leave being shot at while sailing to my brother!
My rationale was that a chart plotter with a good size screen was going to cost a limb. I have a 5" Lowrance GPS on the binnacle but this is a little small for passage planning etc.
My Toughbook CF-19 has built in GPS and an external GPS antenna but I have found the internal works fine inside a GRP Mac.
I also now use it to run my CNC mill since it's just as at home covered in swarf as water!
Beware chart plotters, GPS and laptop/tablet chargers will eat your 12v battery capacity when sailing. If you don't have a dual battery system get a low voltage alarm (or better get a second battery) to save you.
RS232, RS422, RS485 etc.etc are similar serial comms standards. Take a look at http://www.rs485.com/rs485spec.html for techie details.
They can (usually) be made to talk to each other, sometimes with appropriate adapters but it is also an exercise in getting them to talk the same language. (cordless phones can talk to mobile phones or landlines but only if the persons both speak English...)
It is (sometimes) possible to connect RS232 and RS422 devices just by making up the right cable pinout.
see https://www.stratusengineering.com/rs232-rs422485-conversion-cable-conne...
The nice thing about standards is there are so many to chose from!
Dave.
Dave Newton Sailbadthesinner
Hi Rick,
Many thanks.
Imray offer an app called "Boat Instruments" for £6.99 which works in conjunction with their free Chart (now being discontinued) & (the replacement) Navigator apps. It's main role is to help them deal with NMEA info available on wifi networks - I guess it's no longer NMEA but the data is there for interpretation and display in useful ways on the iDevices.
As well as displaying AIS data in the usual way (on the charting software) it has its own customisable "instrument panels" for any other useful data on the NMEA bus - e.g. Wind, depth, heading, etc.
I had bought an old iPad 1 3G for £30 on eBay that happily runs the 2016 version of Imray charts and I still use this as a log (of sorts).
The newer version of Imray software, however, need iOS 8 or above, hence I'm waiting to get my hands on a £30 iPad 2 3g.
Still trying to figure out whether to use GPS from the iPad or the plotter. I was comparing the positions shown on my iPhone with that on my plotter this morning and they seemed consistent.
MacGregor 26M 2009 - Sky's the Limit - Suzuki DF50
Thanks Dave also, only just saw yours after posting.
Yes battery use is almost uppermost in my mind. Fortunately I have 3 good batteries and a programmable low voltage alarm on the plotter. Also have a 50watt solar panel which helps a bit during the day:)
I had read that you could interface RS422 & 232 as you mention and although I tried it it hasn't worked for this application. Quark-Elec, the AIS maker actually make a bridging device for £15 to get over comms with Garmin plotters so it probably is a real issue.
I've ordered one so let's see.
Another plan is to take portable battery charge packs for the iDevices. They're going cheap from Maplins at present, being sold off by the liquidator; plus I already have one. Every little helps!
MacGregor 26M 2009 - Sky's the Limit - Suzuki DF50
Just thought I'd let you know my set up:
I use a brookhouse Imux multiplexer to connect all my instruments and sensors (seatalk and NMEA) together. This then sends the data via wifi to my iPad and iPhone. I run iNavX on both i-devices and I absolutely love it. It runs navionics charts and overlays ais and all my other data. You can download grib and the excellent 'theyr ' weather reports before you leave or when you can get wifi of phone signal. I particularly like that even if everything goes flat on the boat, I still have a good 4hrs of hard use left in the iPad. When it's all turned on position is taken from the boat's. gps aerial and compass but in a squeeze you can use the iPad/phones gps capabilities. I did have to upgrade to an iPad with gps as when you are at sea, positioning is worse than useless without a dedicated sensor in the iPad.
Thanks James, sounds very similar to my set-up except I used a Quark-Elec qk-a024 AIS receiver and so didn't need the multiplexer. My plotter has 2 NMEA 0183 ports and I run both NMEA (for the plotter's track) and SeaTalk (for the Clipper Wind) into my Raymarine st2000 autopilot. The Quark-elec unit (for £69) receives and decodes the AIS data then merges it with the incoming NMEA 0183 stream - which, incidentally, is already multiplexed by the plotter. It then outputs the resulting stream not only via its integral wifi network, to my iDevices etc, but also via usb AND NMEA 0183 which I feed back to the plotter in order to have AIS data available on the binnacle.
Also I discovered that my old iPad 1 3G (with GPS) would actually run the legacy version of Imray Boat Instruments so I'm able to get all my boat data on it: Charts, tides, current, AIS, GPS, true and apparent wind speed and direction, COG, SOG, etc, along with accumulated data.
Just wondering now whether I can figure out a way of controlling the autopilot from the iPad. There must be a way as Raymarine offer a wireless remote device for it - for £450.
MacGregor 26M 2009 - Sky's the Limit - Suzuki DF50
Hi mike. In your scenario, you should be able to use iNavX to send autopilot data on NMEA 0183. My autopilot requires nmea 2000 which I haven’t quite cracked an adapter/emulator yet.
Thanks James, yes there's a good video of using iNavX to control an AP at - https://youtu.be/J7POAPsK-SY
This is simply doing what I already do with my Chinese £8 wifi AP remote.
What I'm looking for is a way to control the AP directly; i.e. As if the iPad is pressing it's buttons rather than what's shown in the video which is, in effect, controlling it via it's track function.
It may be that iNavX has other capabilities in this regard but my feeling is that it's limited to manufacturing and sending NMEA 0183 sentences to "control" the AP.
To directly control the specific AP, in this case the Raymarine ST2000, I'm guessing it would need Raymarine specific language transmitted using SeaTalk.
Judging by their withdrawal of their e85001 NMEA > SeaTalk converter, and their policy of making their AP deaf to the NASA Clipper Wind (to encourage purchase of their, much more expensive wind transducer) I'm guessing that, keeping this "in house" forces the purchase of their £450+ remotes by preventing easy access by iPad software.
The irony is that Apple model this sort of craftiness themselves, as Imray admitted to me when I tried to update my charts on my iPad 1.
In practice I don't need this function so it's really moot; I was just wondering.
Thanks again James.
MacGregor 26M 2009 - Sky's the Limit - Suzuki DF50
I just bought a very old wired seatalk remote. All my instruments are st80 which I love but st50/60/80 would all be compatible with your gear.
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