AIS Questions

Dean Abramson · Post by **Dean Abramson** » Jan 27th, '11, 10:24

I have been researching AIS options, and am confused by a few things. Mainly, what additional antennas I would need.

I would be interfacing the AIS with a Raymarine C80 (with Radar).

I see that some units come with a GPS antenna; I do not understand why I would need that, since the plotter has its own GPS antenna. Also, some units seem to require a dedicated VHF antenna.

Is it generally true that a transponder (as opposed to a receive-only unit) will always require a dedicated VHF antenna?

I would appreciate someone explaining to me what my requirements would be for:
1) a receiver
2) a transponder
To interface with my Raymarine C80.

I am interested in feedback on Comar products, and Milltech Marine. And does anyone have any thoughts on this product:
http://www.milltechmarine.com/AMEC-CAMI ... p_214.html

Also, for a receiver, this looks like a good buy:
http://www.milltechmarine.com/Comar-AIS ... p_187.html
It has a built-in splitter. It would seem that I would need only the unit itself in this case. ?? Comments?

Finally, in the real world, is it safer for me to just stick with Raymarine? (I would prefer not to, since their unit is wicked pricey.)

Thanks,

Dean

Russell · Post by **Russell** » Jan 27th, '11, 12:36

Dean,

Transponders require their own GPS as part of the class-B standard as I recall. They can use other GPS, but all of them will be sold with their own. And with it you basicly get yourself a fully independant backup GPS, its not like its a bad thing.

As for dedicated antenna, it is not nessisary, but absolutely a good idea for both. More so for the transponders, keep in mind it will be transmitting a few times a minute, with a splitter and using your main VHF antenna this will certainly interfere with normal VHF transmission. Besides, a 6' VHF antenna mounted on your stern rail for your AIS also can be used as a back for your VHF should something happen to your masthead antenna.

As for interfacing with your C80, all you need is a bit if light gague wire as it is just NEMA data cable.

As for the units you linked, I have no idea. I have the ACR Nauticast class B and am very pleased with it. I wouldnt touch the Raymarine receiver (I dont thinkt hey make a transponder unless its a recent thing), the only advantage you get for that extra price is it will use Seatalk rather then NEMA, and its not like that does anythign for you other then change which port you connect to on the back of your C80.

Steve Laume · Post by **Steve Laume** » Jan 27th, '11, 13:44

Has anyone looked at the Standard Horizon, Matrix radio with AIS capabilities?

It looks like a very cost effective way of gaining AIS info, especially if you are looking for a VHF upgrade anyway.

Not sure what determines the price on these things but the Matrix radio seems almost too good to be true so I am a bit skeptical, Steve.

Len · Post by **Len** » Jan 27th, '11, 14:21

Steve,
I have a Matrix installed. It works very transparanetly. I am also able to view and use the system on my remote mike. The only glitch I have (and DEAN this is for you) when you are actively using the ais is disconnects the VHF reception(your on a splitter). My view on this particular machine choice is that if you want to update to DSC you might as well add the ais feature for a smaller surcharge rather than getting (updating to) a stand alone AIS unit and a VHF with DSC.
Len

seadog6532 · Post by **seadog6532** » Jan 27th, '11, 15:12

We have the Matrix 2100 DSC VHF with AIS and love it. We don't think you will find a simpler or more cost effective way to get AIS. We have been cruising since November and it is one of the best and most used pieces of gear on the boat. We have a simple Garmin 400c hand held plotter attached for the GPS and have the RAM mic at the helm. Also with this unit you don't need a second antenna. This was an early Christmas present from my wife. Guess I was pretty good last year.

Kevin Kaldenbach · Post by **Kevin Kaldenbach** » Jan 27th, '11, 19:18

The GPS antenna is so that the transponder knows where it is and when you set the unit up you will be required to register where on the boat it is located. We have an ACR transponder and it has worked well. It shows up on both our chart plotters. The additional VHF antenna could come in handy if you loose your radio antenna. A second antenna is sometimes a requirement for off shore racing anyways. Though I have not programed it to do so yet the ARC has the ability to shut off the transponder part of it. This could come in handy if you don't want people to know where you are.

Maine Sail · Post by **Maine Sail** » Jan 27th, '11, 20:02

Steve Laume wrote:Has anyone looked at the Standard Horizon, Matrix radio with AIS capabilities?

It looks like a very cost effective way of gaining AIS info, especially if you are looking for a VHF upgrade anyway.

Not sure what determines the price on these things but the Matrix radio seems almost too good to be true so I am a bit skeptical, Steve.

I have a Matrix 2100 AIS and it works very well as a RX unit interfaced with my Garmin. It shares the VHF antenna and is a simple install and is also one heck of a nice VHF too.

Please keep in mind that the TX rates are NOT the same speed for all vessels TXing AIS. Big moving ships take priority band width over recreational and smaller vessels. Some vessels may only be sending location as slow as every minute or so. In fog this can be disastrous if you try and rely on it solely. Nice tool when used in conjunction with other nav instruments.

Take a look at these two photos that were taken a less than one minute apart. The boat was actually in the position of photo #2 when I took photo #1. AIS is NO replacement for radar just yet....

CruiseAlong · Post by **CruiseAlong** » Jan 27th, '11, 23:10

I own a Comar 200 AIS Class B transponder (reciever and transmitter) and still have a Millitech SR161 AIS receiver. Both work very well. The Comar sends and recieves on two different communication lines to other instrumentation. Your GPS most likely accepts 38K baud "VDM" AIS command sentences which both Millitech and Comar put out. The COMAR has an additional output/input channel (RS232) which can be adjusted from 4.8 to 38K baud which is nice. Both can work with your existing antenna but you must purchase a separate antenna switcher which disconnects the antenna input to the AIS if the VHF radio goes into broad cast. That switch can be more costly than the AIS unit. That is why folks are mentioning the Standard Matrix GX2100 VHF radio. It displays AIS and sends the AIS signal to your GPs and can accept GPS information from the GPS for both display and navigation, and DSC emergency broadcast. The $399 cost for the radio gives you the least costly package but you get the built in switcher, AIS reciever, AIS signal to your GPS and the ability to accept and display the GPS signal on the radio. Since I already had an AIS unit I opted for the Standard Horizon GX2000 which does the same thing as the Gx2100 but does not have internal AIS, it instead accepts an external AIS signal. With less internal hardware the GX2100 can be gotten for about $199 . Truly remarkable radios that really work well when it comes to AIS and GPS interface. Sail Magazine rated them very high in their latest issue. I can't stress how much there is to these two radios. I would suggest downloading their manuals from the Standard Horizon website for further information on their function..it is a great site....

chase · Post by **chase** » Jan 29th, '11, 18:07

Can you set a proximity alarm for offshore use with the 2100 AIS?

Chase

Steve Laume · Post by **Steve Laume** » Jan 30th, '11, 11:35

Chase, I believe you are talking about the single hander's, wake up, you have company alarm.

I am pretty certain the Matrix radio has this feature and it is one of the primary reasons I am interested in the AIS system. You would not be alerted to other yachts, such as yourself, that did not have transmitting capabilities but at least you would get a heads up if there was a commercial vessel in your vicinity.

I know this can also be done with radar but at quite a cost in energy consumption.

This would not replace watch keeping on a short handed boat but would be a very welcome asset to have aboard, to alert you of any large and fast moving traffic coming into your sphere of the ocean, Steve.

Sea Hunt · Post by **Sea Hunt** » Jan 30th, '11, 11:46

In the February 2011 issue of Practical Sailor there is an interesting 3 page article on the AIS system and its impact on personal freedom, privacy, etc. entitled "Big Brother on the Water". It is authored by Ralph Naranjo, a former Vanderstar Chair at the United States Naval Academy.

For those who do not subscribe to Practical Sailor I believe you can order individual issues or articles by calling 800.424.7887.

seadog6532 · Post by **seadog6532** » Jan 30th, '11, 16:47

You can set an alarm on the matrix 2100

chase · Post by **chase** » Jan 30th, '11, 18:32

At this pricepoint, this is very appealing if it is a good DSC VHF radio with a command mic feature. The ability to use DSC or hail by name is a great feature. Sounds like these features are also available at the helm. Thats really useful.

Chase

CruiseAlong · Post by **CruiseAlong** » Jan 30th, '11, 20:23

GX2100 or GX2000....Are all available from the remote extra RAM 3 microphone. It is an extension cord with detachable mic cord, mic cord plug mounting plate....basically everything thing you can see (AIS display too) on the base radio screen is on the remote mic display....The AIS alarm is both based on time intercept and closest distance.
Dana

Dean Abramson · Post by **Dean Abramson** » Jan 30th, '11, 21:52

I have heard that even though ships are required to have AIS transponders, they are not required to use them. ?? Is this just a popular myth?

Also, does anyone have a rough idea as to what percentage of commercial fishing draggers currently transmit AIS?

And very large yachts? (It would seem that the guy who keeps a helicopter on his boat might also splurge on AIS.)

Dean

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