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Old 22-01-2013, 18:18   #1
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New Inexpensive Ais Transponder

i came across this ais transponder today. it's advertised as the lowest cost transponder and also self contained with it's own battery and antenna. couldn't find a price for it.

AIS Identifier

sounds like it's just what i want. i only need an ais to cross the gulf stream at night - florida to bahamas. i just want to be visible to other ships, don't really need or want to track them. so i'm looking for something that's self contained and inexpensive. this one seems to fit.

i know dirt about ais so i'm asking the electronics experts out there to tell me what they think of it, given my requirements. my concern is that it seems to work only on certain 'channels' and i don't know if these are the 'channels' that regular ais works on, so will i be visible to ships if i use this device?

all ais people please advise....
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Old 22-01-2013, 18:53   #2
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Perhaps it is intended for private AIS networks. Like tracking a bunch of fishing gear or research craft?? Does not appear to be what you want for interacting with shipping.
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Old 22-01-2013, 19:01   #3
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Re: new inexpensive ais transponder

Hmmm. A small-vessel AIS "Identifier" that is neither a Class A or Class B transponder.

I'm skeptical, albeit hopeful. Is this deal too good to be true?

Caveat emptor.
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Old 22-01-2013, 19:52   #4
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Re: new inexpensive ais transponder

I was in West Marine the other day and they have a VHF/AIS combo for about $199. It's reciever only but is about the cheapest setup I've seen so far. I'm not too concerned about transmitting, I'm more interested in identifying and being able to call up a ship by name to make sure it's seen me if it's heading my way.
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Old 22-01-2013, 19:57   #5
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Re: new inexpensive ais transponder

It transmits at one watt, which is half of a Class B unit...

It has a built in antenna, which would further degrade it transmission range.

My guess is your transmission would be seen no more than 2 miles from your boat, if it was mounted on the outside of the vessel and much less if it was mounted in the cabin.

It does not have a constant power supply, youhave to rely on a battery.

It does not meet, nor is it approved by the IMO or USCG pursuant to their regulations for AIS.

In my opinion, if you want to use this for safety and collision avoidance, you should look at a Class B unit.
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Old 22-01-2013, 19:57   #6
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Re: new inexpensive ais transponder

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Originally Posted by VirtualVagabond View Post
......I'm not too concerned about transmitting, I'm more interested in identifying and being able to call up a ship by name to make sure it's seen me if it's heading my way.
Vic
Isn't that what a transceiver does automatically?
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Old 22-01-2013, 20:22   #7
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Re: new inexpensive ais transponder

The specifications say:User interface Status LED SOS button with configurable messaging

It appears that the only information displayed where it is installed is a blinking LED. This device appears to only mark the position of its location to other receivers. It is a transmit only device.
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Old 22-01-2013, 22:16   #8
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Re: new inexpensive ais transponder

virtualvagabond - i'm just the opposite. i'd rather be transmitting so those big cruise ships and freighters can see little old me in the middle of the night. i can usually see them by their lights. i'm too busy looking around to spend any time with a receiver screen.

jeremiason - i don't mind the battery power - it claims 120 hours and i probably need one tenth of that. the power part worries me. i want to be seen at least 10 miles and 20 would be better. those big ships move fast in the gulf stream.

so, anybody know if there's a more powerful transmit only ais out there?
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Old 23-01-2013, 06:13   #9
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Re: new inexpensive ais transponder

Quote:
Originally Posted by onestepcsy37 View Post
jeremiason - i don't mind the battery power - it claims 120 hours and i probably need one tenth of that. the power part worries me. i want to be seen at least 10 miles and 20 would be better. those big ships move fast in the gulf stream.

so, anybody know if there's a more powerful transmit only ais out there?
AIS is VHF radio, meaning in theory, it is line of sight... Class B transmits at 2 Watts and Class transmits at 12 watts.

I have a AIS Class B on my boat with a masthead antenna and normally am seen at between 8-12 miles on calm waters... The transmission distance is reduced significantly if the boat is rolling hard... Something to do with the antenna lobe radiation at sever angels, if I remember right...

Anyway, for your requirements, you will need a proper Class B AIS unit for power and an antenna mounted as high as you can get it.
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Old 23-01-2013, 06:19   #10
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Re: new inexpensive ais transponder

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Originally Posted by onestepcsy37 View Post
virtualvagabond - i'm just the opposite. i'd rather be transmitting so those big cruise ships and freighters can see little old me in the middle of the night. i can usually see them by their lights. i'm too busy looking around to spend any time with a receiver screen.

jeremiason - i don't mind the battery power - it claims 120 hours and i probably need one tenth of that. the power part worries me. i want to be seen at least 10 miles and 20 would be better. those big ships move fast in the gulf stream.

so, anybody know if there's a more powerful transmit only ais out there?
Your first statement here is a very dangerous one. Many commercial ships will filter out Class B signals and they will not see you. They are required to transmit a class A signal that you can and will see. You will be much safer going with a receiver and standing a proper watch.

Receivers are cheap now. If your VHF needs updating you can get one that has VHF for about $200 or less if you shop around.

Do not put your safety in someone else's hands.
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Old 23-01-2013, 06:26   #11
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Re: new inexpensive ais transponder

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Your first statement here is a very dangerous one. Many commercial ships will filter out Class B signals and they will not see you.
I'm not sure this is true. Why would a prudent watch commander ignore any Class B AIS? A collision is a collision and will/can injure people, damage vessels and ruin careers.
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Old 23-01-2013, 06:36   #12
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Re: New Inexpensive Ais Transponder

I agree totally with you Tim. The "be seen" function is definitely secondary to the "see" function. We opted for a receive only AIS a few years back in part because of difficulty positioning a transmitting AIS antenna away from our VHF antennas. Would not be without it. At 2am one night, we were 20 miles off Savannah in the midst of about 15 large vessels. AIS showed clearly where they were. Much clearer than radar in my opinion, though we use both together routinely. I figure it is my obligation to keep away from large ships, not the other way around!! That is not to say that I would not have added the transmit function if I could have done so without issue.
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Old 23-01-2013, 06:46   #13
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Re: new inexpensive ais transponder

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I'm not sure this is true. Why would a prudent watch commander ignore any Class B AIS? A collision is a collision and will/can injure people, damage vessels and ruin careers.
I cannot explain why but it does happen. I have a friend who used to skipper 1000' tankers and he verified this. Although he never let it happen on his boats.

Here is a good article from the RYA:

http://www.rya.org.uk/cruising/curre...mallcraft.aspx

Back to the transponder in the OP. Reading the specs, I see no mention of this even being a Class B transponder. I use an AMEC Camino. It is about $600 for the base unit and various accessories you need to install it.

One last question for the OP: What is yours and your crews lives worth?
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Old 23-01-2013, 06:57   #14
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Re: new inexpensive ais transponder

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Originally Posted by Tim R. View Post
I cannot explain why but it does happen. I have a friend who used to skipper 1000' tankers and he verified this. Although he never let it happen on his boats.

Here is a good article from the RYA:

AIS transmissions from small craft | Current Issues | Cruising | RYA
Tim

I was driving commercial boats in San Francisco and never had the need to filter out Class B targets, but I could see the need in parades or opening day ceremonies as an example...

I would imagine as Class B becomes more popular that in areas where there is high vessel traffic, it may happen in order to avoid the collision alarm from going off frequently. But not once you on the open ocean.

But both International and US Rules require the Captain to use all available means for lookout, which has been interpreted to include Radar and AIS.

God help the first Captain who strikes a Class B AIS Target, because he was filtering and therefore not providing a proper look out under both International and US Law.
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Old 23-01-2013, 07:00   #15
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Re: new inexpensive ais transponder

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i'd rather be transmitting so those big cruise ships and freighters can see little old me...
I have to agree with those who say that counting on them to see and avoid you is a really good way to end up being run over. You need to rely on yourself to see and avoid them.

It's not a question of whether or not they're filtering out your signal. It's a question of who is responsible for your safety, and who you rely on to keep you safe--yourself, or the other guy? If you are depending on the other guy... God help you.
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