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Old 13-12-2006, 13:27   #1

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AIS Compliance RANT

AIS certainly has the potential to really help keep large and small ships saver in congested waters. But, like all systems, it is subject to the Garbage-in-garbage-out" rule.

Example, here ins the SF Bay area there is a cool website that shows all of the AIS reporting vessels on the bay in almost real-time.

Recent Ship Positions on San Francisco Bay

I am looking at it right now and it seems like almost every vessel has some error in its reported data.

A large inbound ship has NO data, one of the local ferry boats is listed as carrying Hazardous cargo. Many boats with ther status listed as "undefined". Wildely outdated destination information and ETA's.

All of this I assume is being used by our local VTS. Why don't they insist on correct data? Is this ignorance or just sloppiness? These guys are supposed to be professionals...

Rant complete. Now I feel better

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Old 13-12-2006, 14:09   #2
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Yeah, and I loved that 229' passenger ship which the animation suggests ran into the houses in Belvedere :-))

Used to teach sailing on SF Bay. I betcha there are a LOT more vessels out there than shown by AIS. And, of course, they don't show the sea lions!


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Old 14-12-2006, 00:18   #3
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Don't discount the usefulness of AIS, even with incomplete or incorrect data. I use it as an aid to managing close situations, and for this the important data (position, course, speed) is usually correct. I have seen some errors in reported position, but these will be less common over time.

This fall I visited San Francisco VTS, and had a good discussion and demonstration of how they were using AIS. They are very optimistic about the value of AIS to VTS, and to other boaters as well. They are also very interested in seeing that ship information is properly programmed, to the point that they asked to get a copy of the NMEA data that I had saved during an encounter with a ship that was sending incorrect position information.

Bill, of course you are right, only a small fraction of the boats on the bay are sending AIS reports. But on the high-seas, all the boats do, except for the occasional sailboat, fishing vessel, or military ship. Sea lions, floating logs, and half-sunken containers don't have AIS, either, so you still need to keep a lookout (and all the rest of the obligatory disclaimers).
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Old 14-12-2006, 03:19   #4
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It's a new device and will take for people to get serious in its use. It's nothing to rely on just yet... but it does hold promise as a useful colision avoidance tool.

I have a NSAS receiver and I consider it at this point a novelty... not a naviagtion instrument.

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Old 26-09-2007, 18:16   #5
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Think of AIS as yet one more aid to navigation..along with all the other things you must do to maintain a good watch. No one aid covers everything but when combined with radar, getting on the VHF to confirm what side you want to pass, a watchful eye, a second set of eyes, an electronic chart, plotting to a paper chart, etc, etc, they all add up to something better than one aid alone. Think of AIS as one more tool for the safety/navigation toolbox.

Personally, I would rather see AIS transceivers used by commercial vessels which tend to be larger, faster and therefore more dangerous than yachts. I would rather not see my screen cluttered up with smaller vessels. I know I will catch grief for this but I can just imagine what will happen if dozens of typical weekend yachties start using an AIS transceiver in a relatively small area such as San Francisco Bay. The really important traffic such as catamaran ferries going 40 knots will get buried by 20 foot sailboats going 5 knots. I though see no problem with them buying a receive only unit. Offshore, no problem, get the transceiver. You will not be cluttering up a screen offshore.

For now, it's a relatively rare occurrence to see a yacht with AIS on the SF Bay. For offshore, having an AIS transceiver may just save you from getting run down...especially considering how dim so many of the yacht nav lights are. It's legal to have lights that are brighter than the minimum standard for your vessel. Also, strobes are supposed to be used for emergencies according to the COLREGS. Eventually someone is going to get passed up in a liferaft because the person on watch thought it was another sailboat...if it has not happened already.
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Old 26-09-2007, 18:34   #6
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David raises an excellent point. I suspect what will happen when more and more vessels are transmitting data that more sophisticated filtering collision avoidance features will be included in the software. Without that it will be just so much garbage to sort through and the good stuff will be lost in the noise.

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Old 26-09-2007, 19:06   #7
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Rule 36
Signals to Attract Attention
If necessary to attract the attention of another vessel, any vessel may make light or sound signals that cannot be mistaken for any signal authorized elsewhere in these Rules, or may direct the beam of her searchlight in the direction of the danger, in such a way as not to embarrass any vessel. Any light to attract the attention of another vessel shall be such that it cannot be mistaken for any aid to navigation. For the purpose of this Rule the use of high intensity intermittent or revolving lights, such as strobe lights, shall be avoided.

Sailboats don't need a strobe if they use all the lights that are available to them. In addition to the side lights and the stern light, a sailboat can have a red over green 360 degree lights at the top of the mast. Additionally, you can shine a light at the approaching vessel or on the sail. Essentially, you can legally light your boat up pretty much like a Christmas tree if you want.

Please, stop using the strobes except for emergencies. Help out the people who may be in actual distress. rant.
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Old 27-09-2007, 01:51   #8
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David quotes RULE 36 as per the USCG Nav’ Ctr’s “NAVIGATION RULES” at: Navigation Rules Online
”We have combined the International and Inland Navigation Rules on this site so comparison between the two sets of Rules is easier...”

Specifically, Rule 36 at: Rule 36 & 37: Signals to Attract Attention and Distress Signals
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Old 08-10-2007, 06:00   #9
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Going to sea is my job. Sailing is my passion. I am underway right now on a ship from Scotland to the US.

AIS is the best new devise for collision avoidance for small boats that I've seen in over thirty years of shipping and sailing. Not so much for the information it gives the boat but because of the information it gives the ships. I believe that it is foolish to do open ocean short handed sailing without one. Radar reflectors don't work very well.

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