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Old 23-06-2013, 06:20   #61
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Re: considering an ais transponder, any recommendations?

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I to have witnessed a vessel altering course, but not at 10 miles away. You have witnessed such at that distance?
In open water that's typical. You probably don't witness it much because you're not even aware of it.

The bridge crews are generally concentrated on their ARPA displays and will make a small alteration of course typically about 10 miles out in order to avoid any close encounter. They study you for a while to see if you're on a steady course. With their powerful radars and height of their antennas they see you much further out than you see them. Plus, at 14 - 18 knots, their distance horizon for making decisions is completely different from yours.
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Old 23-06-2013, 06:55   #62
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I've also had them alter course, but before AIS, they would sneak up on me, I'd try to make radio contact. I can specifically remember a few Eastern European voices say to me, yes, we see you dummy and we've altered course 10 degrees to .*. degrees, thanks for the call. Because all I do pretty much is sail in shipping lanes it seems like on coastal passages it happens a lot. Point being, without AIS on my boat, they saw me and took action way before I knew they were there. They're a professional lot as a whole.

On Chesapeake last summer on overnight passage, a couple asked me if I had AIS when I made radio contact. The seas were up and they couldn't always get radar return. I think they really like us having transponders because it simplifies their work. They would have voted for antenna on stern rail in lieu of none at all..... Funny though that they are coming to expect us to have it on little boats now.
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Old 23-06-2013, 06:57   #63
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Re: considering an ais transponder, any recommendations?

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What's the big deal with the separate antenna vs a splitter?

I have a handheld, sat phone, epirb, and other gear so I'm not really seeing the "if the mast goes, everything goes" argument. If the mast is ripped off the last thing I'm going to be worried about is not picking up ais contacts.
Remember it is a "transponder" not just a receiver. My AIS Miltech with Vesper display has a SAR button. I push it and it sends out a message that my boat is in trouble. I can program it too, medical, disabled etc... Ships within range can see it. While not an EPIRB it's just another arrow to have in the safety quiver.
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Old 23-06-2013, 07:05   #64
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Re: considering an ais transponder, any recommendations?

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DotDun:

I see your point of AIS clutter in the Bays and Harbors, but offshore the greater the transmitting distance, the earlier the OTHER vessel will see you.

During our cruising, I frequently saw large cargo and passenger ships alter there course around me. Not because they had too, but because they saw me early enough to do it.

At 10 miles away, a large ship altering course just 1 or 2 degrees will open several miles by the time we are at the CPA.
That's been my experience too! Gives both vessels piece of mind and not second guessing ultimate intentions. I often alter my course too just to give them more room. Works well for everyone.
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Old 23-06-2013, 07:46   #65
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Re: considering an ais transponder, any recommendations?

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You can get the emtrak b100 online for about a $475. Pretty good deal. The Vesper units with seperate displays are nice too. I'd go for a seperate antenna, it doesn't need to be at the mast head.
+1
Good unit, good tech support, and price.

There is a huge amount of detail stuff here that doesn't mean much to me in terms of practical usage.
Sandy and I sail alone and I just felt it was an extra bit of safety gear if either of us ever nodded off on a watch.

We don't have a lot of experience with it yet, but so far we've used it from Chesapeake Bay to Bermuda, and Bermuda to St Martin.
Sailing down Chesapeake Bay it was fun to experiment with it and really useful going into and out of Norfolk.
At sea you'd die of boredom waiting for a ship to liven up your day. I think we saw 3 on each leg. Of the 6, 3 of them made minor adjustments to their headings, even though they probably didn't need to, and the other 3 were no risk situations.

Because I'm a technical dunderhead, I went really simple and just stuck a vhf antenna and the GPS antenna (that comes with the unit) on the doghouse out of reach of the boom. They're probably 10-12' above waterline.

I don't need to know there are ships 20 miles away. It's very unlikely that you'll need to make sail adjustments either because their antennas are so high they've picked up your signal before you're anywhere close and changed direction a couple of points if needed.
I know they're there in plenty time to pick up the vhf and call them by name if I'm the least concerned.

A couple of points...
1) I bought this unit because it was cheap and simple to install and better than a radar reflector. I also liked the idea of being able to call a vessel by name if I needed to.
2) We use it with OpenCPN but couldn't get the latest version to sound the alarm, which is an important feature to us. We uninstalled it and installed the previous version and now we have the alarm working.
3) The GPS antenna comes with a mile of cable. I was about to cut it, but rang their tech support first. The only problems they ever have are with people who have cut the cable! So it's all folded up neatly behind a speaker in the doghouse.
4) The unit doesn't come with an On/Off switch but obviously simple to install one.

The emtrak really is good value for $ in my experience.

Vic
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Old 09-08-2013, 07:40   #66
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Re: considering an ais transponder, any recommendations?

I have a Digital Yacht AIT2000 with their SPL2000 Zero-Loss Splitter. The transponder has both NMEA0183 and NMEA2000, so has you covered either way and the Splitter is Zero loss so doesn't suffer from any degradation from splitting the signal. It also has a USB output for those using a PC. Works really well.
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Old 21-08-2013, 20:46   #67
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I can verify that the 2150 is smart enough to recognize transmissions with it's own MMSI number. It won't display your own boat. Assuming you have the same MMSI number programmed into both units.
As a followup to this, the SH 2150 indeed does ignore an AIS transmitter using the same MMSI number. HOWEVER, for some reason, it still outputs that target's data. So while you won't see yourself on the radio, if you're using the radio's AIS data output for a PC nav program (at least for Coastal Explorer) you will show up, and experience whatever alarm-related problems a boat 0 meters away would cause, which with CE are considerable because with it you can't ignore targets.
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Old 22-08-2013, 06:23   #68
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Re: considering an ais transponder, any recommendations?

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Originally Posted by SVNeko View Post
As a followup to this, the SH 2150 indeed does ignore an AIS transmitter using the same MMSI number. HOWEVER, for some reason, it still outputs that target's data. So while you won't see yourself on the radio, if you're using the radio's AIS data output for a PC nav program (at least for Coastal Explorer) you will show up, and experience whatever alarm-related problems a boat 0 meters away would cause, which with CE are considerable because with it you can't ignore targets.
Have you/can you try it using OpenCPN?

'Own vessel' is suppose to be sent on the NMEA stream, but I believe it's marked differently. I'm curious in your case if the 2150 is sending 'own vessel' but not marking it as such, OR Coastal Explorer is interpreting 'own vessel' incorrectly.

FWIW, the system I have experience with is an EmTrak B-100 transponder with a SH 2150 and a Simrad NSO Chart Plotter. The Simrad is receiving AIS data from the 2150. 'Own vessel' does not appear on the Simrad.
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Old 22-08-2013, 08:54   #69
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Re: considering an ais transponder, any recommendations?

I have an Icom MA-500TR on each boat. I have integrated it into the Raymarine C-80 to display there.

The only down side I have is the GPS antenna is fairly huge.

For the VHF, being a steel boat, I just got a mag mount and plop it down.

This summer I found a bunch of boats, even commercial boats, that don't show up until pretty darn close. I suspect that they have intentionally degraded their setup for some reason. I've been told sailboat racers do that, required to have AIS, but they put the antenna in the bilge.
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Old 22-08-2013, 10:06   #70
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Re: considering an ais transponder, any recommendations?

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For the VHF, being a steel boat, I just got a mag mount and plop it down.

This summer I found a bunch of boats, even commercial boats, that don't show up until pretty darn close. I suspect that they have intentionally degraded their setup for some reason. I've been told sailboat racers do that, required to have AIS, but they put the antenna in the bilge.
I doubt if many boats are intentionally degrading their AIS systems. How good is your mag-mount antenna, and where is it located?

When I was first trying out AIS on my boat I used one of those suction-cup "emergency" VHF antennas, and stuck it to the deck. The performance was horrible, and I could only pick up reliable signals from a few miles range or closer. I soon installed a decent VHF whip on the stern rail, and got vastly improved range. Eventually I installed the AIS whip on the upper spreader and got even better performance.

So, crappy antennas perform poorly. Antenna location matters. I suspect that the poor range you are seeing is due to a poor antenna, and/or poor antenna location. Or, lossy coax cable / connectors.
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Old 22-08-2013, 10:25   #71
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Re: considering an ais transponder, any recommendations?

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FWIW, the system I have experience with is an EmTrak B-100 transponder

I've been considering the EM-TRAK B100. How do you like it? How was it getting it setup. I'm looking at someday getting one and wire it in with a Garmin Chartplotter.
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Old 22-08-2013, 11:28   #72
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Re: considering an ais transponder, any recommendations?

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I've been considering the EM-TRAK B100. How do you like it? How was it getting it setup. I'm looking at someday getting one and wire it in with a Garmin Chartplotter.
Works as advertised. Setup via usb cable and the ProAIS2 software (included). Support has been excellence, emails answered (intelligently) within a day, most within a hour or two.
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Old 22-08-2013, 12:11   #73
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Re: Considering an AIS Transponder, any Recommendations?

MY antenna works fine. I can see some boats 40 miles, land stations more.

SOME boats only show up within a short distance, >3 miles.
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Old 22-08-2013, 18:57   #74
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Re: Considering an AIS Transponder, any Recommendations?

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On Chesapeake last summer on overnight passage, a couple asked me if I had AIS when I made radio contact. The seas were up and they couldn't always get radar return. I think they really like us having transponders because it simplifies their work.
Yeah, I've been asked if I have AIS recently too, and it does sound like they'd like that a lot. Makes me think seriously of getting a transponder.
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Old 22-08-2013, 19:34   #75
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Re: Considering an AIS Transponder, any Recommendations?

A comment was made a few pages back about few support networked GPS input over N2K. It is a feature of the AIS specification that the unit must have a local dedicated GPA input. Hence a compliant unit cannot make use of network GPS input.

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