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AIS--New Price Point

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Initially Posted - 04/02/2009 : 14:40:11

See the [url="http://www.westmarine.com/webapp/wcs/stores/servlet/product/10001/-1/10001/371822/377+207?cid=E090404D"]new West Marine promotion[/url]...

This is the system that commercial vessels now use to identify their vessels, GPS positions, and courses digitally to each other for display on their chartplotters and to enable efficient radio communication. There have been AIS receivers available at prices similar to this one, but this is the first AIS transponder I've seen anywhere close to this price. No doubt others will follow.

If you've ever been in pea-soup fog with commercial traffic (not to mention morons in sportfishermen), you can relate.

Association Port Captain, Mystic, CT
Past member and DPO of C-25 #5032
Now on Eastern 27 Sarge (but still sailing) and posting as "Stinkpotter".

Passage, Mystic, and Sarge--click to enlarge.

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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Response Posted - 04/02/2009 : 15:22:20

This would be a very cool thing to have but it begs some questions. Most of which I think can be answered by "because that's how they made it", but maybe not. Plus I'd have to get another chartplotter or bring one of my laptops on board to use it (I think). Although it says it has NEMA out, so maybe not, I'm not sure if my Garmin will display external data. I know my VHF displays external data from the GPS, and the GPS should display DSC data, so maybe it'll do AIS as well. Have to read up on it.

Why does it need to have two GPS & VHF antennas each? I understand in it's current configuration why it's necessary, but what if I've already got perfectly functional VHF & GPS units with their own antennas? Will they produce a model that uses external inputs/outputs at some point?

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 04/02/2009 : 17:23:08

I dunno, David... I'm not in the market at this point, and my radar is underutilized as it is. (I mostly avoid fog.) I assumed it wants a VHF antenna to send and receive AIS transmissions, and will exchange NMEA sentences with a chartplotter to transmit your location, course, and speed, and show data for other vessels on the chart and on an AIS page if there is one. Your vessel data is programmed into it before delivery.

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redviking
Master Marine Consultant

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Response Posted - 04/03/2009 : 08:02:40

David, I think your Garmin can handle it depending on the model. BUT, I think you have to buy a black box to interface with the AIS. For long distance cruisers, AIS with transmit capabilities makes sense. However, if every stink potter and wind bagger with a grand burning a hole in his pocket decides to "go live" the screen will be cluttered and will render the system unusable. I think a recieve only system is more than adequate for weekend warriors.

sten

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delliottg
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Response Posted - 04/03/2009 : 10:39:09

I don't disagree that a receiver only instead of a transponder would help to keep screen clutter down for everyone involved. However, to get most anywhere I want to go, I have to cross shipping lanes and dodge ferries. In pea soup, not only would I want to know where they were, but I'd want them to know where I was. Thus far we haven't had to deal with this situation, but eventually we will. I've got a horn that I haven't installed to my VHF's hailer yet, but when it is, the radio will automatically output any signals I need. But a horn in the distance is a far cry from a blip on your screen that you know is another boat. That's one of the reasons I went to the effort to find the best radar reflector I could afford. I've also considered active radar reflectors, but for their price I could have the AIS or nearly so, and it seems much more useful.

Even if it didn't talk to my Garmin C-276, I have enough laptops laying around that I could bring one of those on board to display the data.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 04/03/2009 : 11:14:52

Sten, why would it be more "unusable" than radar is now--you're just adding identification, and making it possible for one vessel to hail another on the radio. See an ID by a target on the plotter (with the radar overlay), look it up on the AIS page, see the vessel name, hail the vessel. In nice weather when everyone's out there, they can go incognito.

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Oscar
Master Marine Consultant

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Response Posted - 04/03/2009 : 19:42:39

Good price, that was 3K just a few years ago. I agree that passive is enough for a recreational mariner (until the price comes down to a few hundred.) The AIS computes CPA and TCPA (Time to closest point of approach) and gives you plenty of time to get out of the way, or call them if you want to stand on your stripes (pun intented).

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Sten, why would it be more "unusable" than radar is now--<hr height="1" noshade id="quote"></blockquote id="quote">

BIG difference. AIS picks up data on a VHF frequency, regardless of sea state, weather, land masses, thunderstorms etc. etc. and plots it.

I have almost been run over by 1000' ships that never showed on radar because of sea clutter/rain etc etc.

I have picked up EVERY ship that came within 20nm on AIS.

Edited by - Oscar on 04/03/2009 19:44:24

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 04/03/2009 : 23:28:12

<blockquote id="quote">quote:<hr height="1" noshade id="quote"> Sten, why would it be more "unusable" than radar is now?<hr height="1" noshade id="quote"></blockquote id="quote"><blockquote id="quote">quote:<hr height="1" noshade id="quote">BIG difference. AIS picks up data on a VHF frequency, regardless of sea state, weather, land masses, thunderstorms etc. etc. and plots it.

I have almost been run over by 1000' ships that never showed on radar because of sea clutter/rain etc etc.

I have picked up EVERY ship that came within 20nm on AIS.<hr height="1" noshade id="quote"></blockquote id="quote">Exactly. Sten said recreational users would make it unusable... I'm not convinced. I'd rather have an identified AIS target than a now-you-see-it-now-you-don't unidentified radar target.

Edited by - Dave Bristle on 04/03/2009 23:32:56

Oscar
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Response Posted - 04/04/2009 : 11:09:50

At one point I thought they were going to assign a lesser target status to the recreational vessels. IOW, you show up on the screen with a small target, but there would be limited, or no data. This would keep the clutter down on the screen, and would allow easy identification of big boys, while still painting a target of the small guys so you can look out the window.

Edited by - Oscar on 04/04/2009 11:10:54

Nautiduck
Master Marine Consultant

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Response Posted - 04/04/2009 : 12:05:15

I must say that the thing that scares me the most about our PNW cruising is the thought of getting caught out in heavy fog. One morning at Friday Harbor the fog was so thick that from our slip we could not see the VERY LARGE Washington State Ferry docked less than a hundred yards away. Of course we did not leave the harbor until the fog cleared but it really gave me a good sense of what it would be like out there. We do have a very good radar reflector but clearly that has its limitations. Some day the Nauti Duck will have radar, I just wish the prices would come down a bit.

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Oscar
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Response Posted - 04/04/2009 : 13:00:45

<blockquote id="quote">quote:<hr height="1" noshade id="quote">We do have a very good radar reflector but clearly that has its limitations.<hr height="1" noshade id="quote"></blockquote id="quote">

Yes, they don't see it.

The only way to protect yourself is to see them. Given the choice between radar and AIS I'll take a $200 AIS receiver over a radar any day. The GPS will keep you off the rocks.

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 04/04/2009 : 13:09:18

AIS or no AIS, there's no guarantee in fog--how do you suppose that Coast Guard tug managed to run into the ferry by Block Island last year?? Perhaps "fake right, fake left, go right..." (also known as "shall we dance?") AIS should have enabled them to immediately talk to each other before the excitement started.

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sweetcraft
Admiral

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816 Posts

Response Posted - 04/04/2009 : 16:40:14

We need every tool possible and then just slow down in a fog. Cruising allows me to delay the next leg and anchor. I have monitored the VHF and watched cruisers pop out of the fog in the NW going at top speed and if they were using radar I didn't hear any traffic on the VHF. I do anchor to wait out the fog and have the plan charted where it would be safe before the fog happens. I am very interested in the AIS for safety as these conditions happen and some boats press their luck and then they make the news.

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redviking
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Response Posted - 04/05/2009 : 04:29:48

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Dave Bristle
 Sten, why would it be more "unusable" than radar is now--you're just adding identification, and making it possible for one vessel to hail another on the radio. See an ID by a target on the plotter (with the radar overlay), look it up on the AIS page, see the vessel name, hail the vessel. In nice weather when everyone's out there, they can go incognito.
<hr height="1" noshade id="quote"></blockquote id="quote">

Case in point. My wife and I hauled up the hook yesterday morning at 02:00 such as to take advantage of weather and the current, etc. As we threaded our way out of St. Mary's inlet, we hear a security call from an inbound freighter. However, the freighter appeared to have a million lights all red and white stretching for over a mile.

WTF?

I issued my own security call which was promptly answered by the freighter. Hmmm... Then the freighter did 5 blasts - again WTF? About that time we see three sailboats, one unlit completely and the other two are running an anchor light and a steaming light, and just running lights respectively. We advise freighter of the unlit one and that the other two are a bit off ColRegs. He passes, but yet the mile long red and white parade continues.

Finally we figured it out. They were all sailboats belonging to the same club or something. Probably the light up whatever you've got club.

We watched in amazement as boats with red anchor lights with a steaming light on passed us only to be followed by boats with white anchor lights on and no other lights, followed by vessels with all sorts of weird combinations of running lights sans steaming lights, etc... There must have been 30 vessels or more. Not one of them answered my security call BTW. I did complain about their collective running light issues with no response.

The freighter Captain hails us and we shift to a working channel wherein we commiserate. In 22 years, he said he had never seen anything like it. He didn't know what it was either until he was right on top of them!

Sounds like a case for AIS, right? Wrong. If all 30 vessels were broadcasting, they could have easily blanketed the actual threat - the freighter. Then we have to go back to old school and use radar and the radio to figure it out.

I know, it's only a matter of time before everyone has it. But it's original application was collision avoidance for commercial vessels.

sten

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 04/05/2009 : 11:29:03

Well, let's see... If they all had it, the freighter would've had a clue about what they were before he was "right on top of them". If recreational AIS is differentiatable (?) from commercial AIS, then the screen can highlight the freighter or overlay its symbol on the others. (I guess it isn't, but that's a good idea.) I dunno... I think I'll take all the information I can get. I can zoom in to any target(s) on the GPS screen...

Edit: Thinking about it further, it seems to me the software can differentiate commercial from recreational based on "vessel type" and "dimensions" to highlight various vessels appropriately on the screen. I suspect if AIS gains wide recreational use, GPS or AIS equipment will be programmed to do that. It can also mathematically point out potential problems based on courses, speeds, and even turn rates.

Edited by - Dave Bristle on 04/05/2009 11:41:59

Oscar
Master Marine Consultant

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Response Posted - 04/05/2009 : 20:30:35

<blockquote id="quote">quote:<hr height="1" noshade id="quote">It can also mathematically point out potential problems based on courses, speeds, and even turn rates.<hr height="1" noshade id="quote"></blockquote id="quote">

It does, except for the turn rate. AIS computes CPA (closest point of approach) and TCPA (Time to CPA) I have called a freighter in the middle of the night and told them they were going to run over me in 19 minutes and asked what their intentions were..... (200 miles off shore)... we negotiated a five degree course change on his part for 20 minutes and I saw him go by a few miles off my beam. I don't know if I would have know about him in time to get out of his way without the AIS. (He was coming dead up my stern)

BTW we use something similar in aviation, TCAS (Traffic Colission Avoidance System) and in addition to alerting each other, the boxes communicate and come up with a solution, to avoid the "dance" Dave describes. Of course, here we are talking about seconds...... And yes, the recreational stuff shows up.

Edited by - Oscar on 04/05/2009 20:32:46

delliottg
Former Mainsheet C250 Tech Editor

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USA
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Response Posted - 04/05/2009 : 21:05:54

Oscar,
How did you know the freighter was there in the first place (since it was in the middle of the night)? Is there a proximity alert, or collision course alert? Or is it simply you paying attention while on watch? It would seem that if it's capable of calculating CPA & TCPA, it should be able to raise some sort of alarm when it calculates a collision course, or inside of a danger circle.

Edited by - on

Oscar
Master Marine Consultant

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Response Posted - 04/11/2009 : 14:39:10

Danger circle..... I set it for 20 miles. It's an audio alarm, which, for some reason is a melodic basso fundo that announces "proximity alarm activated". I call him Igor and had him piped into ships' stereo which boomed him from stem to stern...(I was solo and sleeping in the cockpit).

Knowing where he was, and exactly where to look it took about 10 minutes for his masttop light to come above the horizon. As I said it was night. Vis was reasonable, winds 10-15 seas around 6 feet.

Edited by - Oscar on 04/11/2009 14:40:37

redviking
Master Marine Consultant

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USA
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Response Posted - 04/12/2009 : 07:00:03

OK, I'm sold. But you have a receive only unit or do you transmit as well? What model do you have? I want to overlay on my Garmin Plotter and I think I need a black box and a vhf splitter and a black box for the Garmin. Is that correct? Need more info. WM $699 unit is not a finished plug and play system, and I am trying to figure out what all will be required. I don't really care if I have a second screen that is not overlayed, as the alarms and data are all I need anyway and the nav station has room for another toy.

sten

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Oscar
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Response Posted - 04/15/2009 : 20:52:50

<blockquote id="quote">quote:<hr height="1" noshade id="quote">But you have a receive only unit or do you transmit as well?<hr height="1" noshade id="quote"></blockquote id="quote">

I don't have anything anymore.... Got my C-42 just the way I wanted it and then reached the point where keeping it didn't make sense..... Restoring a folding tri right now....

I HAD a receive ONLY. At that time the two ways were many thousands of dollars. They are now coming down in price..... (see the first post in this thread.)

Receive only units for Raymarine or Garmin are compatible with some of their display units. I don't know the details.

What I had, and what is the cheapest way to go is this one:

http://www.milltechmarine.com/products.htm

I had the SR161. I had an old VHF antenna on the rail, feeding into the AIS. Then I had it plugged via a serial to USB converter into my laptop, with USB GPS, where it overlaid on charting software displaying raster charts. Around $250 for the setup, not including the laptop.

Edited by - Oscar on 04/15/2009 20:56:10

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