AIS receiver vs. Marinetraffic.com

D

Dene

New member
Thanks to a recommendation on this board, I've been monitoring www.marinetraffic.com for some time, comparing it's data to what I see from my house. (We have a view of the Columbia River). So far, I've been quite impressed with it's real time accuracy.

Today, we had an experience of using it with an AIS receiver. Situation was this. We're on a Coast Guard Aux. patrol, using a 36' Tolly, with 4 aboard. Our task is to assist 50 Christmas ships in their maneuvers which involved twice crossing the shipping channel. My task is to monitor a secondary chartplotter and marinetraffic.com. It's dark...visibility is good...and there is quite a bit of commercial traffic. Several upbound and downbound within 3 miles of each other. One of their Xmas ship members has an AIS receiver and is calling out positions, ETA's, so as to determine a safe time to cross the channel. He calls an unseen cargo ship a fishing trawler. I'm monitoring marinetraffic.com on a laptop and it identifies the ship correctly...it's speed, size, etc. We were able to call out and correct the mistake....a potentially fatal error.

IMO, save your money if you're considering an AIS receiver. Get a wireless card and use it for this site, among other things.

-Greg
 
Hi Dene,

Neat site! I guess I must have missed that when it was posted previously. I've bookmarked it and will refer to it. I certainly appreciate knowing about it. Thanks.

Best wishes,
Jim B.
 
That is a very cool site!

I will say after monitoring Boston Harbor that the update is not entirely accurate. Meaning, it will show a vessel at 9.8 knots for example, and several minutes later (after several refreshes) the vessel is in the same position. The manual refresh link does not always work. I followed a pilot boat I know well. Some of the boats I run have slips literally beside this vessel. When returning from a tanker, they hustle right into their slip and the site showed them at 9.8 knots, a short distance from their slip, for several minutes. When the site did finally reveal a change in position, it was a significant jump in distance and position.

I only say the above as a point of discussion. I assume AIS is actively updated frequently such that it would show more accurate positions? I have not yet used the system.

I really like the website though. Thanks for sharing.
 
A helpful and interesting site...with some caveats...apparently not all ports are covered. Northern Puget Sound and the entrance to Puget Sound are covered but the port of Seattle/Tacoma is not. So I can see vessels entering Puget Sound and in the San Juans but none in the Seattle/Tacoma area. Nevertheless its one more piece of useful data. Thanks for posting about it.
 
I used that site to track Two Lucky Fish on the Lake Washington cruise yesterday and it worked fine until it "froze" with Tim heading for the locks at 6.8Kts.

I also used http://ais3.siitech.net/VTSLite/AView.aspx
which also tracked him but interestingly both sites occasionally show traffic that the other does not. I can only assume this is because they are not monitoring ALL the shore stations.

A boat mounted unit should be monitoring everyting within its range and updating at the same frequency as the transmitters. Rather a different situation compared to trying to monitor all the ground stations on the planet! So I have to diagree with the concept of using a wireless laptop and depending on someone else's computer system to update the website. Also as Tim has noted on Navagear, not all ground stations can pick up Class B AIS.

I took several screen plots of Tim yesterday but I have no idea how to post them here, maybe I can get them into my photo album. Otherwise I'm sure Tim will have them up somewhere when he has made the mandatory snowmen this morning :lol:

Merv
 
Excellent site. Now I won't get anything done -- being landlocked in the snow and ice in Wisconsin -- now I'll be tracking the ships in warmer waters.

We cruise on the Great Lakes and a site like that would come in handy. Most of the time we are not in close quarters, but it still would be nice to see the ship traffic as we cross Lake Michigan.

A few years back, we almost pulled the trigger on the Satellite Weather system that we had seen on a Nordic Tug. The next year, the Verizon AirCard came out and the need to send in a monthly fee went away with the availability of the Internet as we cruise.

Thanks for sharing the site.
 
colobear":2nx6u80o said:
A helpful and interesting site...with some caveats...apparently not all ports are covered. Northern Puget Sound and the entrance to Puget Sound are covered but the port of Seattle/Tacoma is not. So I can see vessels entering Puget Sound and in the San Juans but none in the Seattle/Tacoma area. Nevertheless its one more piece of useful data. Thanks for posting about it.
Click to expand...

Are you certain of this? I used it to track Puget Sound traffic near Bainbridge and Blake Island last weekend. Real handy with the ferry's, especially since my trawler only goes 8 knots WOT.

As for "real time," if you click on the ship's icon, it will tell you how old the data is. I just know that last night, when we really needed it, it was very accurate.

One thing I didn't mention. On our way home, we encountered a tug that didn't show on the site. I figured something was wrong with his transponder. Other ships around him were displayed.

-Greg
 
Looking at San Diego, there's an interesting variety of ships. All the way from tankers down to a 39 ft sailboat. I understand what the tanker is doing with AIS, but not the sailboat.

The thought occurs: if everybody gets an AIS transmitter does the information become saturated and thus worthless? There are a lot more 39' sailboats than tankers, but I worry more about the biggies than the sailboats. At 25' and trying just to stay out of the way, I might get an AIS receiver, but I think I'll avoid the transmitter.

Boris
 
That site rocks for the mouth of the Columbia! If you click on a target's icon, you can display its track ... some of the freighters in holding patterns off the Columbia River make some interesteing patterns. And, you can see the pilot boat Columbia as it heads out to intercept an inbound ship. Way cool.

About clutter from too many targets: you can declutter this site by deselecting craft types you do not care about. Don't know anything about AIS's capabilities in that regard.
 
One thing to remember is that on a number of vessels, including commercial ships (as distinguished from recreational vessels) the data entered to describe the vessel is wrong. (such as the cargo ship being IDed as a fishing trawler).

As to the issue of too many AIS targets--one can filter out by various perimeters which vessels are shown. Many ships only get a read out of the AIS data, not a plot on the screen. Some harbors in foreign lands require some type of identifier on all vessels above a certain size --for example 26 feet. It is very possiable that at some point we may see that for security reasons.

I would prefer to have an AIS B transciever than just a reciever--you can turn the transmitter off if you wish. When out of congested areas, you will want to be seen by the commercial ships--especially in reduced visability. Internet reception is not available in many places, and the various web sites do not cover the entire cruising areas which we frequent. I don't know what the costs of these web site down loads on the phone are, but there some ISP are adding a very hefty surcharge for any data transmitted over a certain amount--one is 150 GB per month. In the long run, an AIS reciever/transciever would be a better choice. We will see plug and play units for most major brands within the next year and prices will rapidly fall.
 
Ok, this might be a tell-tale sign of getting old (Dusty is gonna be proud of me!), but I'm thinking all this stuff, while cool, is a waste of the reason we go on the water in the first place. Sitting at home and seeing it on the computer is interesting and good, but really having this stuff on the boat?? I don't recall who, but someone a while back said something about how helpful one of these ship spotting sites was when he made the crossing from Poulsbo to Seattle. I made that cossing once. I looked out the window, saw that everything for the entire route was clear, and throttled up on plane. Now don't get me wrong - I'm a gadget guy from way back and I have a lot of cool stuff, but if all of it failed all at once I would still go fishing on the river and not get run over by a ship. I think I would be more apt to get run over by one if I was focusing on my uplinked laptop instead of watching where I was going. Just think of what Columbus could have discovered if he had AIS!!

(You can ignore my rambling above and by all means don't take it personally. It's just an old guy wishing he had some of his boat gadget money back to spend on Christmas. Sometimes I forget my C-Dory is 25' and not 250', but it all comes back when I put it on the trailer and put the thousands of $$ of electronics in the house to sit until spring.)
 
TyBoo":174ffpql said:
Ok, this might be a tell-tale sign of getting old (Dusty is gonna be proud of me!), but I'm thinking all this stuff, while cool, is a waste of the reason we go on the water in the first place. Sitting at home and seeing it on the computer is interesting and good, but really having this stuff on the boat?? I don't recall who, but someone a while back said something about how helpful one of these ship spotting sites was when he made the crossing from Poulsbo to Seattle. I made that cossing once. I looked out the window, saw that everything for the entire route was clear, and throttled up on plane. Now don't get me wrong - I'm a gadget guy from way back and I have a lot of cool stuff, but if all of it failed all at once I would still go fishing on the river and not get run over by a ship. I think I would be more apt to get run over by one if I was focusing on my uplinked laptop instead of watching where I was going. Just think of what Columbus could have discovered if he had AIS!!

(You can ignore my rambling above and by all means don't take it personally. It's just an old guy wishing he had some of his boat gadget money back to spend on Christmas. Sometimes I forget my C-Dory is 25' and not 250', but it all comes back when I put it on the trailer and put the thousands of $$ of electronics in the house to sit until spring.)
Click to expand...

LOL old guy. It's just a tool. Last night, we had the radar fired up, two chartplotters, and most important 3 crew members watching in all directions.

Having made the Poulbo to Seattle crossing many times, it's usually just a look left..look right...let's go crossing. But....if fog rolls in, then it's useful to have all the tools at your disposal. Radar, this site, and chartplotters. One thing the site does is give you the names of the ship. Easier to hail a ship on channel 13 if you know the name. Last night, they were hailed by name, advising them of the Christmas ship location and crossing. All responded. In fog, maybe you can't see them but it's nice to know they can see you, especially if you alert them.

-Greg
 
Dene":3hne8s3j said:
... In fog, maybe you can't see them but it's nice to know they can see you, especially if you alert them.

-Greg
Click to expand...

This reminds me of the importance of a radar reflector. I installed the medium size trilens radar reflector on Napoleon and I know I show up as a good target. I have tested it with large ships in pea soup fog and I show up clear. It is amazing how a good size vessels can sometimes appear as a small target on radar.
 
I see the AIS as a real safety feature in limited visability. If you have radar, usually you can tell closest point of approach and avoid collision. But there are "blind" places where radar does not see around a point or into a passage, and two boats can be converging on a dangerous course. Several times, I just barely avoided being run down by a large ship in just such a situation. Even though the ship would have been visiable on radar and my boat also visiable on radar, the convergence was not apparent. Another issue is where there are fishing trawlers or gill netters (not all are so fitted yet with AIS), but often in the fog it is difficult to know where these boats are going (and this is one of the reasons that rudder angle is included in the data). Finally, I had a situation where a submarine was coming up the straits of San Juan de Fuca and I had to maintain several miles clearance. Frankly, even with Radar, I had difficulty determining what the speed and course of the sub was. This was compounded by the strong current running against the sub.

I agree that the laptop should not take the place of
 
Dene,

When you go on the list of ports Seattle and Tacoma are not listed. The first time I went on the site not a single ship was shown in that port area..none under power, none cruising so it looked to me like there is no coverage there. Now, mea culpa, I just went on the site again and there are many ships shown for Seattle. I sure hope it was just a glitch as having it available for the Seattle area would be very nice. I'll have to try a few times more.
 
I looked at this site: www.marinetraffic.com for a long time this evening and never saw a ship anywhere south of the Port Townsend to Edmonds line. Thought that to be highly unlikely in reality. Went through several refresh cycles, both manual and auto.

Harvey
SleepyC :moon
 
If you go to both of the web sites that have been mentioned here and open them up at the same time, you will notice a number of differences, not just in graphics but in the numbers of boats shown. You will also note that one or the other often has big blanks where they show no boats at all in some areas.
I can ony assume that all of this is due to their "post processing" of the data but it leads me to conclude that I would not rely on it for navigation.

Your boat system may not tell you what is going on in Hong Kong but it will tell you who is within a few miles of you hidden behind an Island or a bigger target. It will also allow you to hail them directly by name and ensure that they can see you.

Not the answer to everything, but one more tool in the box.

Merv
 
This is fascinating stuff but I have yet to see anything on either site from Virginia Beach to St Augustine. I can only assume there aren't any base stations in these areas? This seems hard to believe given there are some major ports along this coast line. I contacted Marinetraffic.com requesting the equipment to set up a base station in my area. According to the website they will supply you with the equipment free if you met their criteria. My neighbor who is and offshore tug Captain for Crowley for what ever reason doesn't speak very highly of the system. He says it's pretty hit or miss from Jacksonville to Puerto Rico where he cruises.
 
Back
Top