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Old 29-10-2013, 10:35   #136
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Re: New Inexpensive Ais Transponder

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Originally Posted by Powerabout View Post
Commercial vessels that have ARPA mandated must have the log connected to the Radar. ARPA wont work without the log
The reason is the col regs are based on the movement of vessels in the water not over the ground

The COLREGS infact make no reference to in that regard. Whether its over teh ground or through the water is irrelevant, in so much that all users should be using the same reference.

Furthermore would you back up this statement "ARPA wont work without the log". IMO ARPA can use either water stabilised or ground stabilised inputs . ( thats their terminology)


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Old 29-10-2013, 11:21   #137
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Re: New Inexpensive Ais Transponder

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The COLREGS infact make no reference to in that regard. Whether its over teh ground or through the water is irrelevant, in so much that all users should be using the same reference.

Furthermore would you back up this statement "ARPA wont work without the log". IMO ARPA can use either water stabilised or ground stabilised inputs . ( thats their terminology)


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read the part that talks about making way and underway
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Old 29-10-2013, 11:26   #138
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Re: New Inexpensive Ais Transponder

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incorrect, AIS provides information that can and is used in collision avoidance. It is not in itself a collision avoidance tool, partially because it is not ubiquitous , though teh IMO "intend" AIS to be such a tool in the future

Dave
I thinks thats your opinion as to why the IMO hasn't yet said its collision avoidance tool, the commercial world would say otherwise.
If you bothered to read the whole document clearly the IMO knows the limitations of it.

This whole converation started as I have tried to pass on information for yachties that a commercial vessel may well not be using AIS for collision avoidance especially on vessels where the AIS is a 3 line display on a box in the corner of the bridge.
For a yacht to avoid a commercial vessel its a great tool not the other way around.
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Old 29-10-2013, 11:30   #139
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Re: New Inexpensive Ais Transponder

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Assuming that you and the other vessel are in the same current:

[explanation deleted]
Actually, I over-complicated that. If you know your own course and speed through the water, and you have the other vessel's bearing and rate of change of range (via radar) you can calculate the other vessel's course and speed through the water. Assuming uniform current, of course.
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Old 29-10-2013, 11:37   #140
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Re: New Inexpensive Ais Transponder

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[...] This whole converation started as I have tried to pass on information for yachties that a commercial vessel may well not be using AIS for collision avoidance especially on vessels where the AIS is a 3 line display on a box in the corner of the bridge.
For a yacht to avoid a commercial vessel its a great tool not the other way around.
Here's what you said:
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My point that you seem to not understand is you cant use AIS for collision avoidance in the real world as it doesn't give you the information you actually need to apply the rules. [...]
Had your your original statement had been clearer perhaps we wouldn't be having this argument.
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Old 29-10-2013, 11:50   #141
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Re: New Inexpensive Ais Transponder

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Actually, I over-complicated that. If you know your own course and speed through the water, and you have the other vessel's bearing and rate of change of range (via radar) you can calculate the other vessel's course and speed through the water. Assuming uniform current, of course.
sure thats the bonus GPS gave us all and that was to enable current calculation, so you can always calculate it but with mass of targets on your radar you can really only use the radar and look out the window tools.

PS you can get 3 axis doppler current sensors/profilers but they are $100k
Used on all drilling rigs and anywhere else you need to know the current.
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Old 29-10-2013, 11:53   #142
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Re: New Inexpensive Ais Transponder

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Here's what you said:


Had your your original statement had been clearer perhaps we wouldn't be having this argument.
Sure but I still stand by my comment and the IMO agrees so might one of the posters as soon and he find out the difference between underway and making way.
ARPA tells you the difference the AIS tells you the reverse ( in current)
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Old 29-10-2013, 13:50   #143
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Re: New Inexpensive Ais Transponder

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In the apparently non-real world where I sail, AIS gives me information that is extremely useful for avoiding collisions. I will continue to use this information, as well as my radar, compass, eyes and ears.
and if everyone did the same the would be far fewer collisions in the marine world. The fact is in most cases it takes two to make an accident
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Old 29-10-2013, 14:56   #144
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Re: New Inexpensive Ais Transponder

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and if everyone did the same the would be far fewer collisions in the marine world. The fact is in most cases it takes two to make an accident
agreed but in most cases it takes one, the other boat the watch was asleep or not there, hopefully MLC 2006 will start to fix those issues.
I heard a very scary story the other day, a Semi Sub/Modu had a tanker bearing down on them, they stopped drilling and moved to the max of the riser so maybe 200' to one side and the tanker went past about 30' away from them, they couldnt see anyone on the bridge - GoM
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Old 29-10-2013, 15:01   #145
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Re: New Inexpensive Ais Transponder

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agreed but in most cases it takes one, the other boat the watch was asleep or not there, hopefully MLC 2006 will start to fix those issues.
I heard a very scary story the other day, a Semi Sub/Modu had a tanker bearing down on them, they stopped drilling and moved to the max of the riser so maybe 200' to one side and the tanker went past about 30' away from them, they couldnt see anyone on the bridge - GoM
that is scary and an example of what I mean by it takes two to make an accident most of the time. Good thing in this case number one wasn't there maybe sleeping but number two was alert and able to shift position even if only by 200 feet. Wow that's close.
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Old 13-11-2013, 11:52   #146
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Re: New Inexpensive Ais Transponder

It seems like this thread needs some input from a actual ship watch stander, so here's an interview with gCaptain founder John Konrad about how AIS is used as an aid in collision avoidance:

Panbo: The Marine Electronics Hub: AIS on ships, words from the gCaptain

Other points:

* Both Class A and Class B AIS do output COG, contrary to "PowerBoat's" declaration.

* The "three line AIS display at the back the bridge" that "PowerBoat" often refers to is the Class A MKD (Minimum Keyboard Display). Most of them are actually more than 3 lines and I think that all of them have data outputs so that target information can be seen on other displays (if the outputs are used). Pilots typically plug their laptops into the MKD as soon as they get on board, both for ship position data and AIS. The MKD can not filter out or ignore any targets by mandated design.

* Screen filtering targets on AIS displays other than MKD's is allowed and fairly common but it does not mean that the target is ignored, only that it's not shown on screen until it becomes a possibly dangerous target as defined by user CPA/TCPA thresholds.

* Some Furuno systems and maybe others do allow an operator to ignore targets by type like Class B, but I don't believe that it's commonly done. It mainly makes sense in limited manueverability situations with lots of small boat traffic where the large vessel simply can not change course for small ones and must focus on staying in channels and avoiding other large vessels.

* I'm told that a case has been adjuticated in the U.K. where a ship was found guilty of not using all means necessary after striking a small Class B target it was ignoring, but I can't find any further information
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Old 13-11-2013, 13:14   #147
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Re: New Inexpensive Ais Transponder

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Originally Posted by Ben Ellison View Post
It seems like this thread needs some input from a actual ship watch stander, so here's an interview with gCaptain founder John Konrad about how AIS is used as an aid in collision avoidance:

Panbo: The Marine Electronics Hub: AIS on ships, words from the gCaptain

Other points:

* Both Class A and Class B AIS do output COG, contrary to "PowerBoat's" declaration.

* The "three line AIS display at the back the bridge" that "PowerBoat" often refers to is the Class A MKD (Minimum Keyboard Display). Most of them are actually more than 3 lines and I think that all of them have data outputs so that target information can be seen on other displays (if the outputs are used). Pilots typically plug their laptops into the MKD as soon as they get on board, both for ship position data and AIS. The MKD can not filter out or ignore any targets by mandated design.

* Screen filtering targets on AIS displays other than MKD's is allowed and fairly common but it does not mean that the target is ignored, only that it's not shown on screen until it becomes a possibly dangerous target as defined by user CPA/TCPA thresholds.

* Some Furuno systems and maybe others do allow an operator to ignore targets by type like Class B, but I don't believe that it's commonly done. It mainly makes sense in limited manueverability situations with lots of small boat traffic where the large vessel simply can not change course for small ones and must focus on staying in channels and avoiding other large vessels.

* I'm told that a case has been adjuticated in the U.K. where a ship was found guilty of not using all means necessary after striking a small Class B target it was ignoring, but I can't find any further information
didnt read my post did you...
If it worked as you think Ben then clearly the IMO would say its a collision avoidance tool which they dont do they?
Do you get extra data yes?
Can it help Yachties from getting out of the way, absolutely
Is it overlayed on Radar, not as often as you think as John has confirmed for you, that is the important point that yachties need to realise.
Is any data better than no data, maybe?
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Old 13-11-2013, 13:16   #148
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Re: New Inexpensive Ais Transponder

Ben,
Thanks for posting the link to interview...I had forgotten about it!!!

My favorite lines in regards to AIS:
Quote:
I welcome this technology [AIS] and, while the claims regarding clutter are valid, electronic navigation is not our primary means of avoiding traffic in busy inland waters. At sea (or with less than 12 targets on the screen). I think professional mariners agree this [AIS] will make everyone safer, especially those boats with a small radar footprint sailing offshore.

And, in regards to general collision avoidance:
Quote:
Ships do care very much about boaters they just *sometimes* don't care to notice them in crowded waters because they have too much else on their minds and (as you said) have few options for maneuvering. In fact, when nearing a small boat with erratic behavior bridge teams are at their most attentive! In open waters small boat traffic is an important concern of all responsible mates.



And this quote here is very telling:
Quote:
That being said, if I had my choice between seeing you on my radar or seeing your AIS info overlaid on my radar... I'd choose the former. SO INVEST IN A GOOD RADAR REFLECTOR FIRST!
Although the advice about radar reflectors IS and ALWAYS will be GREAT advice....Since this was from 2007, six years ago now, I wonder if they/he would change the first part of this??? With many ships now having ECDIS with AIS overlay, and with more Class B AIS signals out there, just wondering if their opinions / experiences have changed in 6 years???






As for the "other points", they are what I, and others, have been saying for years (and what I posted here in this thread a month ago, see post #69..)
New Inexpensive Ais Transponder

And, except for the point you mentioned about some of the older Furuno units (which I understood, their very first generation / version of the FA-100 from 10 years ago, would NOT receive/decode the Class B "static data", but would receive/decode and display the Class B "dynamic data")...
I had NOT heard/read that some of the Furuno units allow MKD filtering by "type", can you clarify or give us models???
Quote:
Originally Posted by Ben Ellison View Post
Other points:

* Both Class A and Class B AIS do output COG, contrary to "PowerBoat's" declaration.

* The "three line AIS display at the back the bridge" that "PowerBoat" often refers to is the Class A MKD (Minimum Keyboard Display). Most of them are actually more than 3 lines and I think that all of them have data outputs so that target information can be seen on other displays (if the outputs are used). Pilots typically plug their laptops into the MKD as soon as they get on board, both for ship position data and AIS. The MKD can not filter out or ignore any targets by mandated design.

* Screen filtering targets on AIS displays other than MKD's is allowed and fairly common but it does not mean that the target is ignored, only that it's not shown on screen until it becomes a possibly dangerous target as defined by user CPA/TCPA thresholds.

* Some Furuno systems and maybe others do allow an operator to ignore targets by type like Class B, but I don't believe that it's commonly done. It mainly makes sense in limited manueverability situations with lots of small boat traffic where the large vessel simply can not change course for small ones and must focus on staying in channels and avoiding other large vessels.

* I'm told that a case has been adjuticated in the U.K. where a ship was found guilty of not using all means necessary after striking a small Class B target it was ignoring, but I can't find any further information
Ben, again thanks for the posting...and it's good to see you here abouts....(I read Panbo, but not daily...

And, if you have any other info (or clarification) about the Furuno models that allow MKD "filtering" or "ignoring" of Class B targets, that would be great...as I've not heard of that...

Thanks.


BTW, just an FYI....
I started out with an AIS receiver (a stand-alone unit) back in 2006, and used it for 5+ years, 12,000+ miles offshore, including two Atlantic crossings, and cruises thru the islands....and then 18 months ago, I upgraded to a Class B AIS transponder (using the Vesper WatchMate display, as well as having all AIS data on radar/chartplotter over-lay), and I can say that it is very nice having the transponder!!

Yes, we ALL must be aware that many things out there (actually, most things out there) do NOT have AIS....but at least getting data from those that ARE sending AIS and sending our own AIS data out, can only be a good thing!!!


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Old 13-11-2013, 13:45   #149
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Re: New Inexpensive Ais Transponder

when the col regs get re written to suit AIS please let me know
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Old 13-11-2013, 14:22   #150
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Re: New Inexpensive Ais Transponder

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when the col regs get re written to suit AIS please let me know
Rule 5 would seem to suggest that you should use it if you have it.

Quote:
Rule 5
Look-out
Every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision.
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