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Old 13-11-2013, 13:46   #151
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Re: New Inexpensive Ais Transponder

I for one DID read your posts, and I have been mostly polite and courteous to you here, but I'm wondering if you, yourself, have read any of the IMO resolutions about AIS???

Because, if all you desire is for the IMO to say AIS is a "collision avoidance" tool, then PLEASE read the IMO's own resolutions, adopted and approved 15 years ago!!!!
Originally Posted by Powerabout View Post
If it worked as you think Ben then clearly the IMO would say its a collision avoidance tool which they dont do they?
And, your desire will be met and the arguments your propagated here in this thread will be moot, as the IMO DID actually approve/adopt AIS as a "collision avoidance" system / tool, back more than 15 years ago!!!
And, here is just some of what they adopted when working out the rules and AIS "performance standards", note THEIR use of the words collision avoidance, in regards to AIS!!!!
I highlighted them in red, for you....


1 Scope

1.1 These performance standards specify the requirements for the universal AIS.

1.2 The AIS should improve the safety of navigation by assisting in the efficient navigation of ships,
protection of the enviroment, and operation of Vessel Traffic Services (VTS), by satisfying the following
functional requirements:

.1 in a ship-to-ship mode for collision avoidance;

.2 as a means for littoral States to obtain information about a ship and its cargo; and

.3 as a VTS tool, i.e. ship-to-shore (traffic management).
This is a direct quote from the IMO....
Specifically from:
(adopted on 12 May 1998)


Poweraboat, PLEASE take note of my use of red font on the IMO's use of the words "collision avoidance"....and also take note of the date that these new performance standards were adopted 12 May 1998...15 years ago!!!

Also, please take note that "collision avoidance" was the #1 requirement of the system, again according to the IMO....

In addition to this IMO document (which, BTW, I found in couple seconds at the USCG site) there are many more IMO documents that state the primary purpose / design aspect of the AIS system is, in fact, collision avoidance....

Now, I'm NOT saying that everybody needs to have AIS on-board or they'll die...
Certainly NOT!!!
(and I am VERY well aware of the plethora of vessels / hazards out there that do NOT have any AIS signals...)

Oh, and as for the ColReg issues...that was already written about and shown NOT to support your "myth"....
Heck, even USCG Rule #5 debunks your "myth"....
USCG Rule 5 - Lookout
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.

Please do not twist my words!!!
Originally Posted by Powerabout View Post
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.
I was asking/pondering whether some of the professional mariner's survey answers would be different now, in light of the fact that now 6 years after that survey there is a much greater percentage of commercial shipping with ECDIS on-board which ARE displaying AIS!!!

Poweraboat, your premise has been proven incorrect by information from the exact, specific source that you desired...the IMO....
And, further, you seem to be grasping at straws (trying to twist my words) in order to stick with the myth/misinformation that you've formed into your own little story...
An intelligent and thoughtful sailor would say "Thank You" for the education, and apologize to me for twisting my words???

And, now that I've educated you in the facts, that the IMO DOES in fact classify AIS as a "collision avoidance" system, I expect that you will promptly apologize to Ben!!!

We are all waiting....

Finally, poweraboat, from one sailor to another....(opps, you're a powerboater....)
Well then, from one human being to another, if you persist in propagating lies and misinformation to the sailing/cruising public, you're liable to butt-up against some that are not as polite and courteous as I am...
And, someday soon, you'll even find postings from me that will start off with something like this: "Not sure what bar stool you've propped yourself up on today ...but what a load of crap!!!"
So, use caution when typing, as I think you've learned here, you are NOT the smartest guy on the planet...not even close to the smartest on Cruiser's Forum...

Fair winds...

s/v Annie Laurie

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Old 13-11-2013, 15:04   #152
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Re: New Inexpensive Ais Transponder


I never expected to see such a spirited discussion about AIS! I thought it was a pretty dry topic! LOL

I am very grateful to those of you who stood up to help correct some of the misinformation going around. As an ex-Navy watchstander, one of my worst nightmares was pulling in and out of Hong Kong on my sub, standing radar watch! The lookout and OOD are marking bearings and ranges to hundreds (out of thousands) of contacts, meanwhile the radar is tweaked and peaked and picking up only a handful of contacts because most of them are all wood junks with no radar reflector and not enough metal in them to show up on screen!

In those instances, (back in the mid 80s to mid 90s) I distinctly remember wishing there was some kind of collision avoidance transponder in place that all vessels would carry (especially small craft) that would make them visible to us, just like IFF does for aircraft and military vessels.

It's only obvious one of the primary objectives of the AIS system is collision avoidance. It's an invaluable tool alongside of all of the other tools one has or should have at their disposal.

It's also used quite often in disputes concerning demurrage and despatch of vessels and delays in docking high value cargo. Portvision, for example, collects all AIS data transmitted along the US coastline and this data is stored in data vaults, which cannot be altered by anyone. As such, it can be entered as evidence into a court of law.

If at any time you are within coastal waters and involved in a collision, chances are Portvision has records of the course and speed of both vessels (and all other AIS equipped vessels in the vicinity) which may be very helpful in determining who did or did not do exactly what, and when they did or didn't do it.

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Old 13-11-2013, 21:52   #153
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Re: New Inexpensive Ais Transponder

AIS can display a lot more than just three lines. When additional information is needed on a vessel, or even just out of idle curiousity, a lot more data can be displayed on a particular target. For instance, a vessel might be RAM. Or NUC. Anchored. Aground. Under sail or motoring. Towing. Fishing. Trawling. True, a lot of this information must be taken with a grain of salt, since it is input by that vessel, but every indication that you might need to keep clear of another vessel is important in decision making and collision avoidance.

Speed and course through the water per se is not really the core issue... speed and course relative to your own vessel, is. Bearing and bearing changes is, too.

All AIS information is useful and none of it should be ignored out of hand until there is some indication that it is erroneous.

I have never been on a ship where it was common practice to filter out Class B AIS contacts, either, and I have seen some pretty cluttered displays.

AIS integration with ARPA is a powerful tool. And yes there is sometimes significant difference between a target's radar generated data and AIS generated data. The prudent mariner assumes the worst case, generally, and maneuvers accordingly.

I will say this.. tension on a ship's bridge can get pretty high when a small vessel or several small vessels are maneuvering erratically. Even when there isn't much a ship can do, or ESPECIALLY when there isn't much a ship can do to ensure a generous CPA, small vessels are watched QUITE closely. The prudent yachtsman will take great pains to avoid confusing the watchstanders on a ship in close proximity, particularly in a narrow channel or a traffic separation scheme. AIS is a good way to say, "Hey ship, look at me! Here's what I am and what I am doing." In mid-ocean it is simple to ensure a mile or more CPA. Inshore, you may be lucky to have a couple of cables.

It has been some time since I have been on a ship as a watchstander where AIS information was not available on the ARPA. Referring to the itty bitty box in the corner, scrolling through the items in the list, is no longer the primary means of utilizing AIS. In that regard, things are definitely improving.

AIS is much more important and much more useful than it once was, and the situation is improving day by day.

I remember a second mate once telling a cadet that his primary job in the event of a collision was to rip out the course recorder and bell logger paper and toss it overboard. (I like to think he was just joking.) With the current level of AIS implementation, this would no longer be feasible. A good thing, right? AIS helps keep everybody honest, and responsible.

This is becoming an interesting thread again. We can all learn something here.
1976 Cal 2-27 sloop, MR WIGGLES
Now with clean, dependable electric propulsion!
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Old 23-04-2016, 18:07   #154
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Re: New Inexpensive Ais Transponder

I was just looking on the web for a cheap DIY AIS tranceiver and found this less than 100 USD AIS receiver made by some NZ cruiser ...
Cheapest AIS RECEIVER SYSTEM for Yachts

Looks great! But I am looking to upgrade my present AIS receiver for an AIS tranceiver class B as more countries in SE Asia require it: Singapore, Thailand and now Indonesia. Anyone knows of any DIY AIS tranceiver, similar to that NZ receiver?

"Condemnation without investigation is the height of ignorance" Albert Einstein
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