SailNet Community banner
  • SailNet is a forum community dedicated to Sailing enthusiasts. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more!

Caution: AIS Apps

4K views 26 replies 13 participants last post by  MarkofSeaLife 
#1 · (Edited)
I recently had a fellow sailor - who is just IN LOVE with his iPhone - show me an app that displays vessel positions received via AIS. He said: "Why should I buy an expensive receiver and chartplotter when I have this?"

Since there may be others who are tempted to forgo the expense and use their iPhone or other mobile device instead of a real AIS receiver and traffic display, here're the answers to that question:

1) The AIS data received on your iPhone, laptop, via the Internet, or by any source other than an actual AIS receiver located in your vessel is posted to the Internet by volunteers who have receivers located in fixed positions (often far from water). I'm one of those volunteers. The vessels you see near Half Moon Bay, CA on marinetraffic.com and aprs.fi probably came from me (look for "N8QH" as the source). My receiver is in my sailboat, from which I upload a continual data stream to marinetraffic.com and aprs.fi via the Internet. And when my boat leaves the dock, I disconnect from the Internet and ... POOF! ... all of the data I am supplying, and seemingly all the AIS-equipped vessels in that area, VANISH. There are no other volunteer receivers that cover the area because the surrounding mountains block reception. This is true for many other volunteer receivers: their receivers are only on part-time.
2) If you think you can use AIS data from a service via your iPhone for collision avoidance, then read the fine print. Here's an example warning posted on marinetraffic.com:

"Vessel positions may be up to one hour old or incomplete. Data is provided for informational reasons only and is not related by any means to the safety of navigation."​

The author of that warning isn't exaggerating or just trying to avoid some obscure legal liability. For the SF Bay Area, there are only a handful of volunteer receiving stations, and the coverage in the Bay is highly incomplete. Large swaths of the Pacific Coast (and most of the remainder of the planet) have no coverage at all. If you don't see any vessels on your iPhone AIS app - that doesn't mean there aren't any vessels there.

So don't cheap out by trying to use your iPhone along with some external service to avoid getting crunched by a freighter! The data is unreliable! It's false security. The only AIS data you can trust is the data received by an AIS receiver located in your own boat.
 
See less See more
#2 ·
Thank you for the helpful warning. It's good to hear my concerns verified by someone who actually feeds the data into the system. I can't tell you how many times people tell me that their boat is "equipped with AIS," and upon asking further I find out that they are running MarineTraffic app on their cell phones. It happened as recently as yesterday in this thread:

...I don't think iOS or Android [chartplotter] apps display AIS targets yet, and I doubt they'll ever do split screen like a Windows or Linux laptop. (marinetraffic.com doesn't pass muster for real-time navigation.) The split screen is great, because I can just focus on sailing without ever touching the computer to zoom in or out.

[Correction: I realize that Android and iOS have some apps that will duplicate the displays of other computers, so it may be possible to use those apps to display AIS targets.]
Marine Traffic is an AIS app for Android.
As I said in my prior post, MarineTraffic is not a navigation quality tool. MarineTraffic uses a network of land-based stations manned by hobbyists at their homes. There can be blackout zones when the stations go down, and there can be time delays in their updates. When a vessel is moving 15 knots up the river, a delay of 4 minutes equates to a nautical mile. That's the difference between being able to tack across the channel and encountering a very uncomfortable situation.

I have confirmed this from side-by-side comparison of my real-time AIS reception with the MarineTraffic app on my phone.

MarineTraffic a nice novelty for looking up pictures and port history of boats, but do not use MarineTraffic for real time navigation!
 
#3 ·
I've noticed that my iPhone app often doesn't display all the targets on the MarineTraffic website, AND there are times when neither of them display tankers off El Segundo that I can see with my own eyes.
 
#4 · (Edited)
Thank you, TakeFive. You are absolutely right. AIS received from marinetraffic.com is only intended for people who live on a coast to identify the boats that pass by their windows.

As a licensed Global Maritime Distress and Safety System Maintainer, it just drives me nuts that anyone would use an iPhone or Android on their boat - that's receiving AIS data from any Internet source - for traffic avoidance. It's like driving down the freeway while only looking in the rear view mirror.

I think it's a symptom of what I call the "mobile device cult" and it's bound to eventually lead to the same serious consequences as texting while driving.
 
#5 ·
Just curious about "...is posted to the Internet by volunteers who have receivers located in fixed positions (often far from water)." I noticed AIS data showing in the Antarctic, are there volunteers there? It seems they would have better things to do than to be feeding data into the Internet. Curious how that works?
 
#7 ·
OK, so I don't have radar and I avoid sailing in the fog. I do have an iphone. A couple of times a year it happens, the fog rolls in. I do check my phone to see what might be out there. I don't expect it to be 100% up to date or inclusive. At least I know what could be heading my way. I do take other precautions like keeping watch and sending out a securitae call.

It's sometimes accurate, though I don't expect it to be, and it's a whole lot better than nothing.
 
#10 ·
...It's sometimes accurate, though I don't expect it to be, and it's a whole lot better than nothing.
There are times when having no data is safer than having bad data.
 
#12 · (Edited)
I recently had a fellow sailor - who is just IN LOVE with his iPhone - show me an app that displays vessel positions received via AIS. He said: "Why should I buy an expensive receiver and chartplotter when I have this?"
I met a fellow like that on the ICW last year and later listened to the radio traffic as the USCG was going out to rescue him because he had just discovered in Masonboro Inlet that the touch screen doesn't work when your fingers are wet.
 
#13 ·
Just a side bar commentary - - The iPhone device is so prevalent with the slick marketing, it is easy to understand how society in general see this device as the modern Swiss army knife; the magic bullet for any and all solutions. There are so many apps that everything is covered:

Think of all the apps available and those to be made, apps for:

Paying for stuff
Finding places and stuff
Buying stuff
Controlling stuff
Driving stuff
doing stuff to other stuff or other person's stuff

There may already be apps designed to take on military missions while making love to your spouse at the same time.

So of course some may be inclined to think an app is just as good as the real thing. AIS vs App.

Thank you for explaining the difference.


Disclosure: I write this from an iPhone. Oh yeah.
 
#14 ·
I didn't think anyone was that dopey to think marinetraffic.com could be used as a real time AIS plotter.

For a start it doesn't calculate CPA.

But marinetraffic.com is very useful to those with an AIS Transponder because when in a port that has coverage you can check that you are transmitting.

Plus you can add a photo or two of your boat so other users can see what you look like.

And as a foreign flagged boat cruising the USA I like to have plenty of records of where I am to keep Big Brother happy. As I'm not an illegal drug running criminal I don't need to hide.

Proper AIS, the transponder, is the best advance in marine safety since GPS and should be a requirement for all vessels going offshore for more than a day sail.
I commend anyone who doesn't have one to start saving up for a proper transponder. The receivers aren't worth a pinch of poop IMHO.

Mark
 
#15 ·
...The receivers aren't worth a pinch of poop IMHO.
I think your opinion is too negative.

AIS receivers do what they were designed to do perfectly well. For small boats sailing in bays and rivers during the day they are fine. Freighters aren't going to steer around a 25 foot sailboat anyway. You can place DSC calls to make your position visible on an as-needed basis.
 
#16 ·
Its amazing i lived this long and never even had a RADIO on the sailboat until 2008 ?

I did up it to a DSC handheld in 2012 after taking Safety at Sea

In all these decades of distance racing MOST of the stuff we need to worry about does NOT have a transponder and the Nuke Subs do not give out info
 
#21 ·
No one is forcing you to spend a few dollars on a particular item of safety.

However please dont denigrate my personal opinion. Receiver only AIS is not worth it. My opinion is from sailing with AIS offshore. Not in rivers. I dont sail in rivers. I do long off-shore cruising.

Mark
 
#22 ·
No one is forcing you to spend a few dollars on a particular item of safety.

However please dont denigrate my personal opinion. Receiver only AIS is not worth it. My opinion is from sailing with AIS offshore. Not in rivers. I dont sail in rivers. I do long off-shore cruising.

Mark
Not denigrating your personal opinion - just disagreeing with it. You said "aren't worth a pinch of poop." I say that's too negative.

End of discussion.
 
#24 ·
IMHO AIS receivers are kind of a waste of money. It is a bandaid fix which is one sided which gives the recipient a false sense of security. Its a kind of gimick where you can see whats around you provided everyone is also transmitting . Its kind of like stealth where you can see....but you arent seen . Maybe it make you feel better you are high tech, b ut it really doesnt solve anything. For a few dollars more you as well as others are all on the same system and playing field and can see each other.

I can only think of the Caprtain of a cargo ship coming up the Chesapeake getting to Annapolis and all these boats with their receive only AIS signals hailing the Captain. Without the transponder he has no clue as to which one of the 20 sailboats cutting across his path are you. So while you hailing him letting him know of your intentions you think you are safe, while he is sitting on his bridge wondering which one you are before him.


In addition I think having radar is actually more important. Radar on the other hand identifies all around you it will provide you everything the AIS does except the name of the vesesel.

The only true means of utilizing this technolgy to the fullest is to have a receiver/ transponsder coupled with radar.
 
#26 · (Edited)
IMHO AIS receivers are kind of a waste of money....I can only think of the Caprtain of a cargo ship coming up the Chesapeake getting to Annapolis and all these boats with their receive only AIS signals hailing the Captain. Without the transponder he has no clue as to which one of the 20 sailboats cutting across his path are you. So while you hailing him letting him know of your intentions you think you are safe, while he is sitting on his bridge wondering which one you are before him...
If you hail him with a DSC call and your have a GPS connected to your radio, he gets your coordinates and knows exactly where you are. (Unless he's TowBoatUS. :mad: ) It's not as much detail as AIS provides, but to say "he has no clue" is an overstatement.

When it comes to electronics, it is easy to think that more is always better. But if you have limited funds, limited cockpit space, limited battery capacity, and limited tolerance for complexity, sometimes you need to make compromises. For some people, an AIS receiver may strike the right balance. And I'll continue to believe that even if I buy a transponder someday.

I don't see any "false security" in having a graphical readout of all vessels over 300 tons on your chartplotter. As long as you realize that there are smaller boats out there too, you will be significantly safer knowing the location, course, speed, and names of all the >300 ton vessels, especially since they are probably the stand-on vessels given their lower maneuverability.
 
#25 · (Edited)
First, let me apologize to MarkofSeaLife. I said that his opinion is too negative, and that was poor wording that could be thought of as "denigrating." I should restate this as my opinion is less negative than his. I have no dispute with his claim that having a full AIS transponder is extremely important in the ocean. The ability to have your vessel seen by others is extremely valuable in the ocean, especially at night or when singlehanding and taking an occasional nap while the windvane takes over. It also valuable in inland waters, though not as much.

However, given a choice between having an AIS receiver and no AIS at all, the AIS receiver still provides significant benefits that are worth considering. It has been 2 years since I priced out a full class B transponder vs. the receive-only options, but at that time it was much more economical to replace my dying VHF radio with the SH 2150GX VHF/AIS receiver. For me, this was the best balance of economy with my needs for the area where I sail. Others who sail elsewhere may have different needs, and the price of transponders may have come down since then (as is the case for all electronics). But I do disagree with any blanket statement that an AIS receiver is "not worth it." It may not be worth it for some, but for others it may meet their needs in an economical way.

Finally, I also disagree with blanket statements that cell phones and tablets are just "toys." While I consider the MarineTraffic site to be unsafe for navigation (whether viewed on a cell phone app, tablet app, laptop website, or supercomputer for that matter), my beef is with the way they collect their data, not with the hardware that it runs on. Cell phones and tablets have become fully capable computers, and as software emerges that can run full-blown chartplotter software with display of all NMEA devices (including AIS targets, DSC calls, and all the instrumentation outputs) they may become viable replacements for dedicated hardware when paired with sunlight viewable displays and waterproof cases. Last I checked, iNavX and Navionics did not yet have these capabilities for full NMEA integration (aside from being a repeater for laptop software), but it may just be a matter of time before they (or more nimble competitors) offer it. It's already part of the offering from turnkey marine electronics companies, and over time the lower cost computer software offerings will have it too.

For example, I no longer use my automotive GPS device. My android phone, running Google Maps with navigation does the same thing, but much better because of instantaneous wireless updates of maps and graphical overlay of traffic status. Point and shoot digital cameras are disappearing because cell phone cameras have improved to the point where the vast majority of people are happy with them, and they offer instantaneous uploads to social websites. Over time I think it is likely that cell phones and tablets could do the same thing for marine electronics, especially on smaller boats where compactness and portability are more valuable. But the software still has a ways to go - MarineTraffic definitely does not cut it for navigation.
 
#27 ·
Finally, I also disagree with blanket statements that cell phones and tablets are just "toys." .
Thanks for the nice words :)

I bought the newish iPad 3 and its near to a toy! if they had put a USB plug in it then a mouse could be used on charting packages for accurate routing. But Apple wanted to hoard all the money to themselves. So chart companies have rolled out half featured programs.
I bought it as a 4th backup GPS and third plotter with good battery life.
It's Ok and fine as a second unit, emergency unit or casual weekend unit. But for full time use its a pain... The charting too inaccurate/slow without a mouse, AIS inability unless I can Bluetooth the AIS unit, on 12 volt with screen brightness up for outside work the battery never recharges, and I can't transfere stuff to my PC, save a PDF or use a word document.

Now with tablets none of the charting mobs see the need for a mouse... It's driving the technology of charting backwards. Raymarine and Garmin should be shivering in their shoes, but they've been given a reprieve.

I am thinking of getting a small laptop as the cockpit and backup computer, and leaving the iPad to facebook and naughty photos. :rolleyes:
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top