AIS Receivers

[waterdog]

Has anyone actually purchased an AIS receiver and integrated it with their chartplotter?   If so where did you get it?  What did you pay for it?  How do you like it?  how was it to integrate?

It seems like a good idea, at least conceptually, but I'm wondering how it works out practically.  Also I'm a little confused.  I look at the wiring diagram for my plotter and it has single input and output wires with a common negative wire for each of two NEMA devices.   Some AIS receivers seem to have RS-232 ports for connection to computers over which the NEMA data flows.   How are the two connected or am I looking at the wrong type of AIS receiver.   

Also has anyone used an antenna splitter?  Are these active devices or simple passive thing that cuts your VHF output in half?   

[Craig Illman]

Steve - First, check out some of the hyperlinks it the message I wrote about DSC in the Fleet 5 section. I got an AIS unit from Milltech Marine. It was $189. They sell a small (6-8") antenna that will probably give you at least ten miles range. I put a small whip antenna on the pushpit, I use a splitter to hook up my FM radio and left my VHF alone. I was able to see ferries at Friday Harbor from Spencer Spit on the east side of Lopez. I have a range of about 15-20 miles or more.

I multiplexed all my NMEA0183 gear, but your AIS doesn't need NMEA0183 input and even though most AIS run NMEA0183 V3 at 38400 baud, the Milltech unit can be configured to run at 4800.

It's basically differential output, so you should be able to connect the common negative between the devices and connect the AIS output to the chartplotter input.

It's a great add-on to your chartplotter! Feel free to contact me offline.

Craig

[Stu Jackson]

Steve, you can find Craig's article via this: http://c34.org/bbs/index.php/topic,4145.0.html

[waterdog]

Excellent.  Thanks.   The article was actually part of my inspiration.  It didn't focus on the AIS installation, so I hadn't realized Craig had actually installed it.   

We have ferries here that come around corners doing 20 knots and tugs with unlighted tows that are just 3 white lights against a background of city lights.  So poor man's radar seems like a good idea.  Then the only thing I'll have to worry about are the damn logs and other idiots like me :)

Since I've got to go spelunking in the aft cabin to hook up the plotter to the new DSC radio, I thought it  might be a good idea to set up the connections.   

Craig did you buy the SR-161?   What does the NEMA serial interface look like physically, is it just two wires?   

I ran a 4 wire cable when I installed the plotter last year.  So I'm using a + and - and have two spares.   If I connect one of the spares to the NEMA 1 output - that will serve my VHF's need for position data.  If I connect the other to the NEMA 2 input - that would give me AIS data into the plotter.  Everything shares the same common - terminal.   Am I missing something?  Is this a lot more complicated than I think it is? 

Do I need to run another wire for incoming DSC data to display on the plotter?  I think I do.  I'd hoped to avoid that particular treat.  I should keep going, I'll answer all my own questions.     

And wait.  I'm not done with silly questions.  Does your Garmin actually display AIS and DSC targets on the chart?   I'm just reading through the owners manual (500 series) and it seems to reference lists and tables but doesn't have any screen captures of target vessels displayed on a chart. 

Thanks!

[Stu Jackson]

Wait, Wait, Don't Lie to Me!  [Name of a popular PBS radio quz/comedy show]

You guys up there actually sail at NIGHT???

[waterdog]

Stu.   Maybe I'm missing something, but if I leave after work and sail over to Doc Morgan's Pub on Bowen Island and enjoy a pint of pale ale, a salad and the calamari, the sun has pretty much set.  So the way I figure, might as well enjoy another pint and let my eyes adjust to the darkness.   Then it's always worthwhile to sail out to Passage Island and watch the moon rise over Mt. Baker behind the backdrop of the city skyline.   It never occured to me that maybe one isn't supposed to sail at night.   I thought that's why they went to all the trouble of putting up those navigation lights and whatnot.    I've only ever dumped one spinnaker in the drink in complete darkness.   There is nothing more exhilirating than blasting along at 6 knots and managing to see the darkness of a 3 ton log while you still have time to turn to avoid it!   

And in the peak of summer we have the fireworks festival.   That brings out hundreds of boats most of whom aren't practiced at night navigation.  Get's really messy when somebody figures it's OK to cross behind those 3 white lights. 

[waterdog]

Wait a minute.  I've been out to Chicago a few times and they invite me to drive a boat and we sail all night just to go and drink rum at some bar called the Pink Pony at some island in Michigan.   So this whackiness is not some strange west coast Canadian thing.   Do you mean to say that you don't go sailing at night down on the Bay?

[Craig Illman]

Steve - yes, you should be able to use the same common reference channel for In & Out of the Chartplotter. The SR-161 has a DB-9 serial output, pretty sure female, you'll just need to connect to pin 3 TX and pin 5 ground. I picked up a DB-9 male plug at Radio Shack, maybe you'll need to visit Canadian Tire?

Yes, AIS targets show up as red triangles. I've yet to see a DSC event. Last summer, crossing Rosario Strait in the fog, the AIS let us avoid a tug/tow and we just waited for the ferry to pop out of the fog bank behind us coming into Thatcher Pass. It's still no substitute for radar, but radar can't show you the ferry coming around the corner. You'll appreciate it.

I'm not going to engage in the sailing at night discussion. I've seen way too many large pieces of wood to get too comfortable about night passages, especially after spring tides and big blows. Then there's crab pots!

Craig

[Randy and Mary Davison]

Steve, I can't comment on your particular installation like Craig can but I sure am a believer in AIS.  You probably saw my write-up some time ago about using the Shipplotter AIS program on a PC with a modified scanner for a receiver.  Last summer it paid off for us a few times.

We had just left Anacortes to head for Bedwell Harbour (I see you're in Vancouver and know the territory) and were running late so we just tossed everything in the boat and headed out.  In Guemes channel we went from a bright sunny day to a pea soup fog just as we were heading into Rosario strait.  I turned on the radar and immediately saw a huge reflection a couple of miles to the north heading for us at 15 knots or so.  I fired up the AIS program and could see the name of the vessel, the fact that it was being herded by two tugs, and that it was a 1000 foot long oil tanker headed for Anacortes.  If it turned for Anacortes, it would clear us.  If it headed down the strait, it was bore sighted on us.  It was a simple matter to call the ship on the VTS channel by name and ask if it was, in fact, going to make the turn.  It was and all was clear.  I could have called VTS and figured out who the ship was and where it was going but  preferred to have the info available real time.

We use AIS every time we cross Haro strait to avoid being surprised by the fast traffic turning the blind corner at Turn point.  We also use it going through Dodd Narrows, Active Pass, and the other blind, high current passes.  It's great to be able to see the big ferries ahead of time.

Virtually all US commercial vessels and big international ships use AIS.  I did notice that the further north we go toward Port Port Hardy, the fewer smaller vessels use it.  You can count on cruise ships, ferries and big tankers, freighters, and other giants.  You can't count on fishing boats and small and mid sized tugs.

AIS started out for me as a curiosity but has turned into a real benefit in crowded shipping lanes.  Go for it.

Randy

[rirvine]

I have been using AIS via the Milltech Marine receiver with my MAC bases MacENC navigation software very successfully on San Francisco Bay for about 2 years. It is comforting to know where the ships and ferry are, where they are going, and how close they will pass and when that might be.  Makes crossing them while racing really easy.

I have the AIS receiver connected to my main VHF antenna through an active splitter – disconnects AIS box from the antenna when the VHF transmits.  In fact the active splitter is between the antenna and both the AM/FM radio and the AIS receiver.

A fun and very useful toy!

Ray

[canuck]

The poor man's radar. Guess I'll have to add it to the list...just as I was down to the Honda E2000!

Yes, nighttime sailing....phosphorescence.....nature's light show and it's legal!  Our own reality show...is that a tug with a tow?

The nav lights aren't put on just for show...or are they? You mean we shouldn't be doing this?

[Stu Jackson]

This "traffic" where you sail at night is enough to confirm my plans to sail out at sea during darkness.  I'll plan to close the coast only during daylight.   

Since you gentlemen have such good systems, perhaps any or all of you would care to share in the form of a Tech Notes article, with pictures and the like.  Thanks.

[waterdog]

Yes, nighttime sailing....phosphorescence.....nature's light show and it's legal!  Our own reality show...

Ah when the squid fill up Tonedos Bay in Desolation, I've often thought of loading dingies up full of German tourists at night and bringing them on "Steve's Electric Squid Tours" at $500 a head.  I could make a killing...

[Craig Illman]

A couple pictures from yesterday, not taken at the same time. The red triangles on the Garmin are AIS targets. The second picture is a WA State Ferry, that we need to avoid. On the runs down at Seattle, they're often accompanied by USCG Ribs with twin Honda 250's and a 50 caliber deck gun. I'm also still trying to ascertain on the 600 ft tankers if the GPS coordiantes are for the bow or bridge.

Craig