Why I Have AIS and Cautionary Note

[Rick D]

In a recent trip to Catalina, and trying out the Open CPN software, I took a couple of shots of the laptop. The first is of the Long Beach / Los Angeles CA harbor area where I am berthed. You can see the amount of traffic via the AIS markings on the chart. The second shot shows the AIS reading of a tanker steaming southwest at 13 knots out of the traffic lanes a mile and a half from me near the west end of Catalina. In the AIS read out, you can see that the tanker states it is moored. This seems to happen a lot. The important piece of the AIS information is the speed and heading anyway. If the pleasure vessel transponders become popular, as they already seem to be, the clutter will make AIS a lot less useful IMHO.

 

[Dan Johnson]

Rick D...

I follow the AIS chart here on the Chesapeake to see what's moving and how fast they're going. I didn't know big ships could drag anchors so fast either.

Check out how congested Norfolk Va is if you get a chance. You'll find every type designation squawking down there and will have to zoom in quite a bit to separate the signals!

 

[Tim R.]

I do not know a lot about AIS but I would imagine it is most useful off shore. I use eyes, ears and radar for near shore.

 

[Steve Dion]

Rick: How do you dodge a stationary moving target?

 

[Rick D]

You take a 90 degree stationary course. Simple, Huh?

 

[chuckwayne]

Tim,
I find it really useful in Portland where the tankers must drag the dock out to sea as they head out the ship channel while tied to the terminal dock!

 

[Ross]

The trnsmissions between two ships:
Ship #1 Bright light directly on my bow turn right.
Ship with bright light. Unable to comply please turn right 15 degrees.
Ship #1 this the US Navy Guided Missile Frigate Nathan Jones , Change course at once .
Ship with bright light This is Nantucket light ship . Your Call.

 

[Manny]

Rick, just curious - what receiver are you using or how are you picking up the AIS signals and how did you interface it with the computer? Also, what charts are you using? I just loaded Open CPN on an old Mac laptop I had and downloaded the charts from the NOAA site. I'm using an "ancient" Garmin GPS 12 through a Keyspan serial/usb converter. I tested it out this weekend and it seems to work well and it was pretty accurate.

Manny

 

[Ross]

I think that pleasure boats in a working commercial harbor should be as careful as a long tailed cat in a room full of rocking chairs. Nobody cares where you are as long as you stay out of the way.

 

[Rick D]

I am using a very basic Smart Radio SR 161 single channel from Milltech Marine. It is interfaced to my Vista (argh) laptop and the GPS engine is some $30 generic from e-bay. The charts are NOAA. It is a simple set up. I might have opted for something more sophisticated, but I am very surprised how well this has held up over two years and... how inexpensive the whole thing is. I had only expected to play with it, but it is oh so much more powerful than that and I use in in seriousness for any significant trip. It has saved me many a false dodge and concern.

 

[Buck420]

I am using a very basic Smart Radio SR 161 single channel from Milltech Marine. It is interfaced to my Vista (argh) laptop and the GPS engine is some $30 generic from e-bay. The charts are NOAA. It is a simple set up. I might have opted for something more sophisticated, but I am very surprised how well this has held up over two years and... how inexpensive the whole thing is. I had only expected to play with it, but it is oh so much more powerful than that and I use in in seriousness for any significant trip. It has saved me many a false dodge and concern.

I'm here at Little Creek, Va (next to Norfolk Harbor) and have exactly the same Milltrech Marine AIS receiver as Rick (although I imput it into Nobeltec Vis-Navigator on a Dell desktop w/ XP,at my nav station .... running off my inverter).
I agree w/ Rick; it's a wonderful help, especially at night. I also found it extremely helpful comming back across the Fla Straights from the Bahamas 2 years ago at night. Heavy ship traffic runs north and south off the South Fla coastline. Knowing speed, heading, CPA, etc of those moving lights at night certainly does reduce the "fear factor".
A problem around the Lower Ches Bay is that Navy (& most CG) ships (for obvious reasons) don't turn on their AIS... nor are commercial fisherman required to have AIS.
And, as Rick says, more and more pleasure boaters (especially the rich power boat guys) are installing Cl-B AIS transponders.
So, the ones we need arn't transmitting and the ones don't, are :Liar:.

 

[SanderO]

I was an early adaptor of class C and I rarely see all and the correct (static and dynamic data). It appears to be a rather (no pun intended) hit or miss system. AIS can give you good information, can give you inaccurate information, incomplete information and can give you NO information. All this adds up to UNRELIABLE information of the entire environment.

I believe this is a great potential for collision avoidance, but it can only be assumed to give one a tad more data and not the complete picture of your surroundings. DO NOT expect AIS to paint it all.

Radar when tuned and working properly is more likely to "paint" the local environment since most vessels and static targets will return some target or return. It's a passive system and does not require a captain to program it. But he has to interpret it. Unlike a fog signal which is also an active system and requires human intervention and interpretation as well.

I believe fog signals can be automated based on the content of moisture in the air as they seem at Stonington CT for example, which seems to sound long before a dense fog sets in. If this is true the same system could (and should) be adapted on vessels over a certain size making their fog signal into a passive system.

Of course, all these passive systems are prone to failure and error and create another layer of false "assurance". As noted many times, the prudent skipper uses as many resources as possible, redundancy whenever possible and evaluates all the data and uses his own experience and judgment and (S)HE makes the decisions on how to proceed. We must be careful not to fall into the faith in technology trap. As sophisticated as it is, all electrical/electronic systems fail on some level and can easily lead to a false sense of security.

A word to the wise is sufficient.

 

[Gail R]

I use eyes, ears and radar for near shore.

No radar at all on our boat, so we rely on eyes, ears, and nose. And I think the waters would be at least as safe, if not safer, if people would avert their eyes from whatever screen they are glued to and take a look around. If you are not sure if/how something is moving, take a relative bearing, wait a minute or two, the take another one, and compare the two.

Seems AIS isn't always right, if it's showing something moored when it is actually moving.

Rant on:

I've been in a loooong debate on a couple other boards with some clown in the PAC NW who insists that since we do not have every gadget known to man (he calls them "systems") on our boat, that we are a "tragedy... waiting to happen."

The concept of averting his eyes from his instruments and actually looking at what's going on around him is completely foreign. It's amazing that we have survived for hundreds of years with relatively few mid-sea collisions considering we didn't have every toy in existance.

Rant off.

 

[Buck420]

Well Gail R,
I could not agree more that a good pair of eyes, attached to a captain w/ experience and common sense is the best equipment ever known. But this humble captain would like to have all the help he can get to keep bad things from happening to him and his boat.
Gail, if you are happy sailing w/o electroncis, ... more power to you.
And SanderO, if you feel that radar is best, ... fine by me.
To each his own.
As for me, even with it's (few) short commings, I'll take AIS (and everything else I can use) when I'm out there; especially at night in the shipping lanes....
but that's just me.

 

[Gail R]

Well Gail R,
I could not agree more that a good pair of eyes, attached to a captain w/ experience and common sense is the best equipment ever known. But this humble captain would like to have all the help he can get to keep bad things from happening to him and his boat.
Gail, if you are happy sailing w/o electroncis, ... more power to you.
And SanderO, if you feel that radar is best, ... fine by me.
To each his own.
As for me, even with it's (few) short commings, I'll take AIS (and everything else I can use) when I'm out there; especially at night in the shipping lanes....
but that's just me.

Granted, in Norfolk, between commercial ad military ships, you have a lot more traffic to be concerned about than we do here in Maine. OTOH, we have a lot more fog up here.

My point was that some people get so mesmerized with all their gadgets and toys that they fail to get their head out of the boat and take a look around.

 

[Buck420]

Granted, in Norfolk, between commercial ad military ships, you have a lot more traffic to be concerned about than we do here in Maine. OTOH, we have a lot more fog up here.

My point was that some people get so mesmerized with all their gadgets and toys that they fail to get their head out of the boat and take a look around.

We DO (occasionally) have fog down here (most often in the Fall)... but nothing like your's .. your's is legendary! ... and I admire you guys for being able to keep from bumping into 'whatever' while out in it.

I also agree w/ you that, people (including myself) don't keep watch nearly as well as they should, but, (at least in my case) I can't blame it ALL on looking at the gadgets and toys. I almost ran into a channel marker a few weeks ago 'cause I was reading ... ... and anyone's who's gone down the ICW has run aground because of just a few moments of inattentiveness (playing w/ their toys?? ... or whatever )

 

[Rick D]

My Point Exactly

these things are aids and nothing more. I have no chartplotter in the cockpit. Only my radar (which repeats waypoint info). Where I am, there are long stretches of nothing, so there isn't much to bump into once you are out in open ocean. What I thought this would be useful for (the AIS) was night racing when ships are often offshore where the racers pass. Cruise ships for example often just have minimal steerage headway while they kill time. Tankers transfer fuel, supply vessels go back and forth, barges are pushed and pulled. These things are much less of a concern if you know what they are and speed / course. That saves time in racing if you don't have to change course. And, sometimes it is hard to pick out the running lights if they are lit like a Christmas tree. That is the next big plus of AIS. When returning to a commercial harbor at night, it is easy to miss running light against the city clutter. Radar and AIS is a big help in that regard. Finally, I try to make life easier for the commercial guys since they are out trying to make a buck and I'm just having a good time. So, by all means keep a good lookout, use common sense and be aware the electronic data isn't always accurate. Speaking of lookout, on a return trip from Mexico this year, my watch was below and one of the guys got up to check on the duty watch. He found all three asleep. So much for lookout.

 

[SanderO]

I don't say that a captain should not use as many information resources as possible to make his passage safe.

I am saying that at this stage relying too much on AIS is not wise. Electronics go whacky, they are turned off, they short all sorts of issues including software and GPS positioning issues come into play. Radar is not perfect and IS and electronic device and needs to be interpreted.

Don't be overly confident. Be prudent and cautious and prepared. That's all I am saying here.

 

[RichH]

I use a Milltech SR161, a Mac laptop, MacENC nav program, etc. using NOAA ENC/BBS charting.

As another poster stated, AIS along the busier sections off the East Coast is a real plus ... the real plus is the indicated NAME, etc. of the ship .... which I then call on VHF to ascertain their course/intentions, etc., and to let them where I am at night and in bad conditions. Just the ID of the NAME of the ship to call is for me the real benefit.

 

[geoffschultz]

The status of the ship (moored, underway using engine, sailing, towing, etc) is input by the crew and should not be considered to the accurate. I've seen lots and lots of ships with "moored" as their status and they're making 17 kts...What is important is the calculated CPA (Closest Point of Approach) and TCPA (Time to CPA) which are calculated. Of course there's a lot of other useful information, but if the two of you aren't on a potentially dangerous course, then it's just interesting data.

-- Geoff, who just switched from an AIS receiver to a transceiver