Rick R.
Contributing Partner
And a man with three watches is thief......:nerd:
AIS on the Chartplotter
- Thread starter Rick R.
- Start date
And a man with three watches is thief......:nerd:
Class B Transceiver and AIS antenna troubleshooting
Thanks for the article link. The article raises good points. The lower output of the Class B AIS (2 watts) was partly responsible for some of my concerns about whether my AIS is operating or not. I tried Marine Traffic initially when testing my Class B and there was no display of my vessel, although several (larger) boats within 200 yards of mine were displayed. Eventually I found that the nearest monitoring station was over hill and dale up in Bellevue. As I was about as far south in Seattle as you can go, I suspect the problem was not with my unit, but simply the range or terrain to the monitoring station. I tried Vessel Finder and was able to see the plot of my boat very reliably.
What brand and model of antennas are you using for AIS? I assume that the Matrix 2100 and 2200 AIS transceivers are using your masthead antenna and sharing it with the communication functions of the radio. So you would have a single coax from the transceiver and no external duplexer. I have a dedicated AIS antenna back near the stern on an arm off the radar mast. It's a Shakespeare 5215 Squatty Body. Shakespeare also makes a dedicated AIS antenna, the 5215 AIS which is tuned for the upper end of the marine frequencies where AIS transmitters are assigned. It is identical to the regular 5215 in appearance.
Thanks for the article link. The article raises good points. The lower output of the Class B AIS (2 watts) was partly responsible for some of my concerns about whether my AIS is operating or not. I tried Marine Traffic initially when testing my Class B and there was no display of my vessel, although several (larger) boats within 200 yards of mine were displayed. Eventually I found that the nearest monitoring station was over hill and dale up in Bellevue. As I was about as far south in Seattle as you can go, I suspect the problem was not with my unit, but simply the range or terrain to the monitoring station. I tried Vessel Finder and was able to see the plot of my boat very reliably.
What brand and model of antennas are you using for AIS? I assume that the Matrix 2100 and 2200 AIS transceivers are using your masthead antenna and sharing it with the communication functions of the radio. So you would have a single coax from the transceiver and no external duplexer. I have a dedicated AIS antenna back near the stern on an arm off the radar mast. It's a Shakespeare 5215 Squatty Body. Shakespeare also makes a dedicated AIS antenna, the 5215 AIS which is tuned for the upper end of the marine frequencies where AIS transmitters are assigned. It is identical to the regular 5215 in appearance.
Yes, the antenna is apparently important.
I'm using the VHF antenna at the mast truck, with the Vesper splitter so it also accommodates VFH radio and am/fm. Vesper is emphatic about the need for the splitter, which is $250 and 12v powered.
But--it's just the VFH antenna that came on the boat. It can't be the correct one.
I seldom see ships more than 8 miles away, and very rarely at 20 miles, even with no land mass. Many ships appear and disappear from the AIS at about five miles.
I'm not sure, but judging by what others report, I think my AIS would be much improved by having some expert advice and installation analysis.
I'm using the VHF antenna at the mast truck, with the Vesper splitter so it also accommodates VFH radio and am/fm. Vesper is emphatic about the need for the splitter, which is $250 and 12v powered.
But--it's just the VFH antenna that came on the boat. It can't be the correct one.
I seldom see ships more than 8 miles away, and very rarely at 20 miles, even with no land mass. Many ships appear and disappear from the AIS at about five miles.
I'm not sure, but judging by what others report, I think my AIS would be much improved by having some expert advice and installation analysis.
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My AIS unit provides the SWR value for the antenna, if it is connected to a laptop with the diagnostic software that came with it. Not an advertised feature, but pretty handy.
My installation seems to be good but there have been times that I could see other nearby "Class B" boats on "ship finder," but not my boat. Well, I am beyond the reach of any ground station most of the time, now. I can generally "see" commercial shipping coming up the river from 15 miles away or more, and that's through canyons and around mountains.
Based on some odd strong VHF transmissions that I've heard, I suspect that the Coast Guard has some sort of repeater system for their own use on the Columbia/Snake inland waterway. I wonder if that has anything to do with it. I tried to find any information on it once and came up blank.
My installation seems to be good but there have been times that I could see other nearby "Class B" boats on "ship finder," but not my boat. Well, I am beyond the reach of any ground station most of the time, now. I can generally "see" commercial shipping coming up the river from 15 miles away or more, and that's through canyons and around mountains.
Based on some odd strong VHF transmissions that I've heard, I suspect that the Coast Guard has some sort of repeater system for their own use on the Columbia/Snake inland waterway. I wonder if that has anything to do with it. I tried to find any information on it once and came up blank.
Re: range and gps signal
Drinking a beer here in sunny Seattle Worshington, at a balmy 66 degrees F. To see how well my handheld VHF signal is (I have it connected to my AIS for a GPS signal), I completely covered it with a stainless salad bowl, and then a fleece blanket over that. It was still able to pick up a GPS position, to my surprise.
I also placed the AIS on the max range (10 nm) and it was picking up boats to about 5 nm. I looked at my Boat Beacon app for reference, and there were several boats within the 10 nm range that the AIS wasn't picking up. It could be because I am in a harbor surrounded by geography. I'll test it out some more in open water.
Mark
Drinking a beer here in sunny Seattle Worshington, at a balmy 66 degrees F. To see how well my handheld VHF signal is (I have it connected to my AIS for a GPS signal), I completely covered it with a stainless salad bowl, and then a fleece blanket over that. It was still able to pick up a GPS position, to my surprise.
I also placed the AIS on the max range (10 nm) and it was picking up boats to about 5 nm. I looked at my Boat Beacon app for reference, and there were several boats within the 10 nm range that the AIS wasn't picking up. It could be because I am in a harbor surrounded by geography. I'll test it out some more in open water.
Mark
Website or AIS App positions
Some old positions are kept plotted for quite some time as the last position known for a boat, on AIS websites. On some websites there may be a setting that controls how long a stale position remains after the last was received. I don't have the Boat Beacon app but I understand it's pretty cool. If I search for my boat on Vessel Finder I can see a position that is days old. They show old positions with red text for the date-time.
Regarding antennas, I borrowed an antenna analyzer and ran SWR and impedance measurements between 140 and 176 MHz on the two 5215s that I bought. I found that they were basically right at 2.0:1 SWR at the high end of the Marine frequency band. They were better at the lower end, about 1.7:1 or so. These are OK numbers for a marine radio with 25 watts output. The Class B AIS by Raymarine doesn't like to have greater than 2.0:1 SWR as measured by the unit (and per the manual) and will record an alarm, suspend transmissions for a time, and show a red status light above SWR of about 2.4:1.
As toddster said, there are PC-based programming and troubleshooting applications that can help diagnose or . Raymarine uses proAIS2 (free download) and via the USB port on the unit, you can monitor the SWR and a bunch of other stuff. I have seen up to 3.7:1 SWR (alarm, red status) and successful transmissions at up to 2.4:1 SWR. After observing my AIS performance on Vessel Finder over several days I am convinced that wet weather affects my SWR, making it higher. Once it dries out the SWR seems to settle right at 2.0:1.
I also believe there are AIS relay stations for the areas where it is needed, due to terrain or distance. From my house I have recorded "coordination" reports from an otherwise unknown station at Point Robinson (Vashon-Maury Island) and from a station near Bremerton, WA.
Some old positions are kept plotted for quite some time as the last position known for a boat, on AIS websites. On some websites there may be a setting that controls how long a stale position remains after the last was received. I don't have the Boat Beacon app but I understand it's pretty cool. If I search for my boat on Vessel Finder I can see a position that is days old. They show old positions with red text for the date-time.
Regarding antennas, I borrowed an antenna analyzer and ran SWR and impedance measurements between 140 and 176 MHz on the two 5215s that I bought. I found that they were basically right at 2.0:1 SWR at the high end of the Marine frequency band. They were better at the lower end, about 1.7:1 or so. These are OK numbers for a marine radio with 25 watts output. The Class B AIS by Raymarine doesn't like to have greater than 2.0:1 SWR as measured by the unit (and per the manual) and will record an alarm, suspend transmissions for a time, and show a red status light above SWR of about 2.4:1.
As toddster said, there are PC-based programming and troubleshooting applications that can help diagnose or . Raymarine uses proAIS2 (free download) and via the USB port on the unit, you can monitor the SWR and a bunch of other stuff. I have seen up to 3.7:1 SWR (alarm, red status) and successful transmissions at up to 2.4:1 SWR. After observing my AIS performance on Vessel Finder over several days I am convinced that wet weather affects my SWR, making it higher. Once it dries out the SWR seems to settle right at 2.0:1.
I also believe there are AIS relay stations for the areas where it is needed, due to terrain or distance. From my house I have recorded "coordination" reports from an otherwise unknown station at Point Robinson (Vashon-Maury Island) and from a station near Bremerton, WA.
I believe that the EM-Trak and Raymarine AIS units (perhaps others?) are the exact same device with a slightly different casing. And pricing, of course. I'd guess that the same software should work for all similarly-shaped units.
Just to clarify my previous comment, the whole Columbia/Snake waterway, upstream from Portland is Dark Territory for internet apps, because nobody appears to operate a ground station link. But on the chart plotter, I can routinely see vessels 15 miles out.
Here's a surprising (to me) factoid gleaned from a random web search: Commercial vessels in the US are not actually required to broadcast an AIS signal until March 2016. I've encountered a few that don't. Notably those towboats that push the huge hopper-barges full of gravel around the lower Columbia (Knife River Corp?) and some pile-driving rigs.
Just to clarify my previous comment, the whole Columbia/Snake waterway, upstream from Portland is Dark Territory for internet apps, because nobody appears to operate a ground station link. But on the chart plotter, I can routinely see vessels 15 miles out.
Here's a surprising (to me) factoid gleaned from a random web search: Commercial vessels in the US are not actually required to broadcast an AIS signal until March 2016. I've encountered a few that don't. Notably those towboats that push the huge hopper-barges full of gravel around the lower Columbia (Knife River Corp?) and some pile-driving rigs.
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Bill Tanner
Member I
Apple Ipad Air 2 128 GB Wi-Fi & celluar
Hello, I have just purchased a 1977 Ericson Cruising 31 and I am looking at some electronics as whets on their is old. I have some air miles and have been looking at www.mileageplusawards at the Apple iPad Air 2 128 GB with wi-fi and cellular capable, they sell for about $ 800 but I have enough air miles plus another $200. hundred and I can get this. I understand that it is a backup unit in addition to charts.
Will I still need a gps and will this unit have AIS if I download the right app? Can anyone give me some advise on this? Thank You Bill
Hello, I have just purchased a 1977 Ericson Cruising 31 and I am looking at some electronics as whets on their is old. I have some air miles and have been looking at www.mileageplusawards at the Apple iPad Air 2 128 GB with wi-fi and cellular capable, they sell for about $ 800 but I have enough air miles plus another $200. hundred and I can get this. I understand that it is a backup unit in addition to charts.
Will I still need a gps and will this unit have AIS if I download the right app? Can anyone give me some advise on this? Thank You Bill
The GPS in the iPad will work pretty well on its own, but I wouldn't depend on it as the only one on board. Well, for day-sailing it's probably enough. You cannot get "real" AIS with just an app. If you have a cellular data signal, you can get some AIS info from the internet with "ShipFinder" and the like, but its functionality depends entirely on how close you are to one of the base stations and how frequently that base station uploads its data to the internet. The nearest base station may not have line-of-site to your location, so the freighter bearing down on you may not appear on the screen! Where I live, there is cellular data, but there are no base stations at all, so that approach is useless.
If you eventually build an instrument network, including an AIS unit, you can link your iPad into that network with a WiFi multiplexer. With the right app, you can then see the chart, your position, AIS data, all of your instrument data, and control the autopilot. I have one waiting to install and am planning to use the iPad rather than the laptop for the control unit this year. The advantages are - 1. with its waterproof case, I can keep it right in the cockpit without worry, and 2. It should use a lot less power than the laptop - hopefully it will run all day without depleting the house battery. But I haven't done it yet, so can't report honestly about it.
Actually, I gave this iPad to my Mom for xmas a couple of years ago. She passed away last year, and it came back to me. It has taken this much time to convince Apple to unlock it for me, even though I had the original receipt, in my name!
Edit: My first year with the Ericson, I got by with a depth gauge and an iPhone 3!
If you eventually build an instrument network, including an AIS unit, you can link your iPad into that network with a WiFi multiplexer. With the right app, you can then see the chart, your position, AIS data, all of your instrument data, and control the autopilot. I have one waiting to install and am planning to use the iPad rather than the laptop for the control unit this year. The advantages are - 1. with its waterproof case, I can keep it right in the cockpit without worry, and 2. It should use a lot less power than the laptop - hopefully it will run all day without depleting the house battery. But I haven't done it yet, so can't report honestly about it.
Actually, I gave this iPad to my Mom for xmas a couple of years ago. She passed away last year, and it came back to me. It has taken this much time to convince Apple to unlock it for me, even though I had the original receipt, in my name!
Edit: My first year with the Ericson, I got by with a depth gauge and an iPhone 3!
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Can you say more about this? What device are you using to multiplex the NMEA data to TCP/IP (that the iPad can access over WiFi)? I've seen a few on the market (Digital Yacht was one I think), but still wondering if it can be done some other way.
I got the shipmodul unit with SeaTalk and NMEA 0183 inputs and NMEA 0183 and WiFi output.
Another hypothetical way to do it, if you have older Raymarine instruments (as I do) is with the Raymarine SeaTalk to NMEA 0183 bridge unit, which can be had on eBay for a few bucks. Some of the units on my network have limited multiplexing ability (The DSC radio and the AIS unit) and the RM Bridge has an RS232 port. So it ought to be possible, in a limited way, to channel everything to the laptop through the serial port and then possibly broadcast that through an ad hoc WiFi network to iThings. e.g. I think a laptop running MacENC can send data to an iPad running iNavX.
Anyhow, before I could execute that kludge, I got the Shipmodul mux. Some client wanted me to spend Saturday morning in the office doing something for him instead of sailing, so I looked up the price of the mux and charged him that.
Rick R.
Contributing Partner
On the way to the Bahamas
We were leaving Pensacola Pass Tuesday in thick fog. My friend does not have AIS onboard so I pulled out my iPhone and started the Marine Traffic App. Thank God we had it! There was a huge Navy Trimaran Warship coming in the pass less than 1/4 mile off our bow.
As as mentioned in earlier posts, the apps have coverage holes in them. As far as safety is concerned, I would put AIS as a top priority for anyone who navigates in the same waters as commercial shipping.
Now I will go back to my Cruzan and cigar
We were leaving Pensacola Pass Tuesday in thick fog. My friend does not have AIS onboard so I pulled out my iPhone and started the Marine Traffic App. Thank God we had it! There was a huge Navy Trimaran Warship coming in the pass less than 1/4 mile off our bow.
As as mentioned in earlier posts, the apps have coverage holes in them. As far as safety is concerned, I would put AIS as a top priority for anyone who navigates in the same waters as commercial shipping.
Now I will go back to my Cruzan and cigar