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Old 24-10-2012, 13:52   #31
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Re: Type "A" AIS for Yachts?

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Originally Posted by nigel1 View Post
Dockhead,
Filtering is carried out on the ECDIS

. . . .
there is no way that I can filter out a target based on size and speed. Both the ECDIS and Radars have a tick box in the AIS setup window "Filter Class B". That's all we can filter.
I happen to have just had furuno commercial gear installed on a boat I am project managing.

Just below is a shot of the filtering screen. In addition to the primary CPA and ETA filters, it has tick boxes for type of AIS (A, B, ATON, SAR Aircraft . . . .) and filtering for speed and length and max range. So at least this one can filter based on length.

Click image for larger version

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Whether these filtered targets 'wake-up' when inside the CPA limit is also user select-able. You have these three options:
• OFF activates no AIS targets inside the CPA limit
• ALL activates all AIS targets inside the CPA limit
• FILT activates the AIS targets inside CPA limit that meet the conditions set for CPA auto activate.


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So, you can in fact filter out targets AND never have them 'wake up' or 'alarm'. Now how many are doing that or not is another question.

The class B VesperWatchmate (which I have on my own boat) has (I think) more clever filtering than this commercial Furuno unit. You can pre-define situations (like anchor, harbor, coastal and offshore) and pre-set a all the filtering parameters for each situation, and then just quickly toggle to the pre-defined situation, rather than having to play around with each individual parameter.

Something I found interesting is that the max number of targets it will displace is 240, and above that it automatically goes into filtering based on whatever aspect is set in the priority box (also in the screen below).
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Old 24-10-2012, 14:44   #32
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Re: Type "A" AIS for Yachts?

Thanks Evans, never seen that degree of filtering.
What model is it, and are the filters on the AIS unit, or on a connected ECDIS/radar.
Find it a bit worrying that degree of filtering. Imagine tracking a target with as close CPA but crossing ahead, and it slows below the minimum speed filter, then with those filters, its gone from the AIS. Hopefully the watchkeepers are also using other means of collision avoidance.
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Old 24-10-2012, 14:46   #33
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Re: Type "A" AIS for Yachts?

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Originally Posted by mbianka View Post
Dockhead:

My Vesper Watchmate display sounds an alarm that I can then mute and also has various settings for the type of area I'm sailing such as harbor, coastal and a setting for when I'm anchored. There are also other settings I can set that I have not yet explored. I also adjust the range on it which cuts down on the amount of ships in view in places like New York. But, as a new one comes in range the alarm will sound again. I find I'm not staring at the AIS screen but, when the alarm goes of I take a quick look and see why it went off and make adjustments as needed. I've noticed the commercial ships I encountered seem to be doing the same. It seems to me any commercial Captain is going to have a lot of explaining to do if he has a collision with a boat equipped with an AIS transponder either A or B. But, the important thing is even if they do filter your boat. You can also take the corrective action because you have their course, speed, CPA information too! And there name so you can contact them on radio.
I also have a VESPER MARINE Watchmate class B transponder/receiver. My antenna is 48 feet up and I see class A vessels at 60 miles. SO WHAT. At 6 miles per hour its still many hours before I care. As Mbianka notes, the Watchmate has multiple filter options so you don't have to deal with non-threat vessels in a crowded waterway. It operates at 3 watts and has a self-contained GPS so it is autonomous. It can feed a network also so its signal can be shared. It also operates as a really fine anchor watch - also at low power. Class A is overkill.

Another thing about the Watchmate - it is the easiest piece of tech I have ever used. You do not need to read anything to find your way around the panel and screens.

AIS WatchMate Transponder *** Buy on line here ***

Vesper Marine
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Old 24-10-2012, 14:56   #34
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Re: Type "A" AIS for Yachts?

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Originally Posted by nigel1 View Post
Thanks Evans, never seen that degree of filtering.
What model is it, and are the filters on the AIS unit, or on a connected ECDIS/radar.
Find it a bit worrying that degree of filtering. Imagine tracking a target with as close CPA but crossing ahead, and it slows below the minimum speed filter, then with those filters, its gone from the AIS. Hopefully the watchkeepers are also using other means of collision avoidance.
It's an FEA-2107 ECDIS.

The AIS box itself only has the CPA and ETA filters - as you said above. But practically speaking, the way this is mounted and used, no-one will be looking at the AIS box (and it is not wired into an external speaker to make the alarm hear). The ECDIS filtering will be the operative filtering.

There is surely going to be a court case sometime when filtering comes up after a collision. I am not so bothered by the display filtering per say, but I am by the ability to completely turn off the alarms on the filtered targets, never to wake up again.

But it's a somewhat difficult trade-off. If you have alarms going on all the time in crowded waters you will just start ignoring them. That's worse than just ignoring the specific ones you have filtered. And if you force a 'target wake-up' at a small CPA (say .5nm) the ship may not have time or space to be able to react in any case.
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Old 24-10-2012, 15:14   #35
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Re: Type "A" AIS for Yachts?

Thanks for the info.
I would like to see an ECDIS/AIS combo which allows a specific target to be de-activated. We have the problem of working in close proximity to other vessels, and we are continually setting of each others AIS alarms. As you say, the watch keepers becomes acustomed to just hitting the alarm silence button, or they set the CPA alarms to minimum.
Ive not seen the Furuno FEA 2107. Although nearly all our nav and comms equipment is Furuno, the ECDIS is produced by a company called Telko. The product is referred to as TECDIS, which I think is the result of co-operation between Telko and Furuno


And thanks to all for the Vesper Watchmate, had not even considered that one in my search for a transponder, looks like a very good unit, and not much more than the Raymarine unit I was considering. The dedicated display is a plus
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Old 24-10-2012, 15:17   #36
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Re: Type "A" AIS for Yachts?

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Originally Posted by nigel1 View Post
Thanks for the info.
I would like to see an ECDIS/AIS combo which allows a specific target to be de-activated. We have the problem of working in close proximity to other vessels, and we are continually setting of each others AIS alarms. As you say, the watch keepers becomes acustomed to just hitting the alarm silence button, or they set the CPA alarms to minimum.
Ive not seen the Furuno FEA 2107. Although nearly all our nav and comms equipment is Furuno, the ECDIS is produced by a company called Telko. The product is referred to as TECDIS, which I think is the result of co-operation between Telko and Furuno


And thanks to all for the Vesper Watchmate, had not even considered that one in my search for a transponder, looks like a very good unit, and not much more than the Raymarine unit I was considering. The dedicated display is a plus

The Watchmate will let you deactivate any target.
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Old 24-10-2012, 15:25   #37
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Re: Type "A" AIS for Yachts?

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The Watchmate will let you deactivate any target.
Thanks, but I dont think my employer will want me to change the AIS installation, but its tempting.
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Old 24-10-2012, 19:31   #38
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Re: Type "A" AIS for Yachts?

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There are both class A and class B transponders. I may be misunderstanding your post, but I think you talking about the differences between class B receivers and Class B transponders.
OK, I see, my mixup. Class B's are also transponders, I was confusing them with receive only. Anyway, the fact that all commercial vessels worldwide are required to have AIS makes this the most important tool for avoiding collisions that we have. We should all get AIS!
Folks, there is no such thing as a Class-B Receiver! There are Class-A transponders, Class-B transponders, and AIS receivers. The receivers will receive both Class-A and Class-B signals.

Also, all modern AIS equipment will see Class-B transponders. Some of the older stuff will not decode Class-B "static" information (vessel name, callsign, dimensions), but the Class-B data for position, course, and speed will be decoded on all modern AIS equipment, since the AIS messages that carry this data were standardized a long time ago.
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Old 24-10-2012, 20:41   #39
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Re: Type "A" AIS for Yachts?

Having toyed with the same idea I will stick to B for the reasons posted by others, I'll use the difference for the deposit on a new sail.

Our screens are covered with targets using class A. They can see us but they absolutely don't care as they just have right of way in the Singapore Straits. I'll try and take a pic and post it but I don't have one now.

My unit has its own GPS receiver and antenna and I find I get targets at great distance. The ones I'm interested in are within 3 miles anyway. One advantage I learnt recently was that when the main GPS antenna dropped offline (data bus failure) the position in the chartplotters was being fed by the AIS unit and this happened seamlessly, just the refresh rate slowed down a bit.
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Old 24-10-2012, 21:01   #40
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Re: Type "A" AIS for Yachts?

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I think A is great. I can see A units from at least twice the distance!

If I were buying an active unit (and if we could afford A which I believe are pretty expensive) I would buy one.

b.
I would say that 99.99% of that range distance is that the larger ships carrying class A also have their antennas 70' high.

My record so far is a Class B signal at 60 miles, received from a tall ship, with the antenna on their mast. The extra power of A might get a little bit more rang, but I just don't see how the extra $1500 or so would be worth it for the recreational sailor.
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Old 24-10-2012, 21:25   #41
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Re: Type "A" AIS for Yachts?

This thread has been mind boggeling in the amount of information given. Could someone give me a rough idea of how much it would cost to outfit a small to medium size sailboat with a new radio and class b transponder? Or can an older radio be tied to a class b transponder. I am not a big fan of high tech stuff ( I love my sextant) but AIS sounds like a really good safety factor. Any help will be welcomed.____Grant.
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Old 25-10-2012, 00:15   #42
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Re: Type "A" AIS for Yachts?

I like the Class B transponders, because I can see the big boys a bit before they see me, and can adjust my course so that when I do pop up on their displays they don't have to change course. There are some downsides, like I am always labeled as a sailing vessel, even when I am motoring, but that's the FCC's fault.

The Vesper Watchmate is an awesome piece of kit. Built by sailors for sailors, and very user friendly and intuitive. One of the best features is the screen which shows the relative positions of the vessels at CPA--you can tell when your CPA is 0.2 miles whether that means you are trying to scrape across the bow of a big ship, or comfortably taking his stern.
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Old 25-10-2012, 00:20   #43
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Re: Type "A" AIS for Yachts?

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This thread has been mind boggeling in the amount of information given. Could someone give me a rough idea of how much it would cost to outfit a small to medium size sailboat with a new radio and class b transponder? Or can an older radio be tied to a class b transponder. I am not a big fan of high tech stuff ( I love my sextant) but AIS sounds like a really good safety factor. Any help will be welcomed.____Grant.

This thread led me to look at the Vesper Watchmate, which looking at the wiring diagram, does not have a connection to a VHF radio. If your looking for a standalone AIS Transponder, this bit of kit may be ideal. If you google the name, should be able to see the price.
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Old 25-10-2012, 00:40   #44
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Re: Type "A" AIS for Yachts?

If your radio has a red emergency button then it can be tied in to ais/gps though the value of doing that will vary greatly depending on the radio.

You can get a Class B AIS transponder for about $450

To that you'd want to have one or more devices to display the info like a chartplotter.

Or a stand alone vesper display is $100 or so

but if you were to do that the watchmate might be a better choice, certainly easier to install.

or a Standard Horizon GX2000 radio for about $200
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Old 25-10-2012, 05:58   #45
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Re: Type "A" AIS for Yachts?

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This thread has been mind boggeling in the amount of information given. Could someone give me a rough idea of how much it would cost to outfit a small to medium size sailboat with a new radio and class b transponder? Or can an older radio be tied to a class b transponder. I am not a big fan of high tech stuff ( I love my sextant) but AIS sounds like a really good safety factor. Any help will be welcomed.____Grant.

Our installation (Class B Furuno FA-50) includes its own GPS antenna for positioning and its own VHF antenna for transmitting... no connection to a separate VHF radio required. Needing some way to display the AIS data suggests a chartplotter or something, if the AIS unit you pick doesn't have it's own display.

A DSC-capable VHF radio is of course a good thing, and I assume it's possible to route GPS data via either NMEA 0183 or NMEA 2000 (better) from an AIS system to the radio.

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