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Old 15-05-2013, 14:34   #1
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Please turn your AIS off when docked/moored/anchored

I sailed by Newport this morning and had 53 collision warning alarms. 51 of them were docked/moored pleasure craft, while two were ships underway that were important for me to be able to follow.
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Old 15-05-2013, 14:39   #2
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Re: Please turn your AIS off when docked/moored/anchored

Evans, can't you filter out the ones at anchor, etc? Or set a minimum speed for them to be recognized as a threat?

My older Watchmate does these things...

But I agree that turning them off when at rest seems a good plan.

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Old 15-05-2013, 14:44   #3
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Re: Please turn your AIS off when docked/moored/anchored

It seems to me that the problem is not that non-moving vessels are transmitting AIS signals; the problem is that you haven't changed your alarm criteria for the harbor area. Personally I would consider turning off the alarm in harbor, or at least reducing the alarm circle to a small radius (e.g. 20m).

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Old 15-05-2013, 14:52   #4
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Re: Please turn your AIS off when docked/moored/anchored

I turn off my AIS receiver when in harbor. I find it is very distracting with hundred of boat symbols lighting up on the chart plotter. I trust my eyes withe the surrounding.
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Old 15-05-2013, 14:59   #5
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Re: Please turn your AIS off when docked/moored/anchored

I just reviewed my AIS manual; there are two types of collision alarms on the Simrad AI50. The first is an "intelligent" alarm that calculates CPA (closest point of approach) and TCPA (time until closest point of approach); this should work in harbor with a tight alarm circle. The second is a "dumb" guard zone; any signal within the zone triggers an alarm. This isn't so useful, as the circle has to be large enough to warn in time to maneuver, and doesn't distinguish between moving and stopped vessels.

Do you have both, and which are you using?

Greg
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Old 15-05-2013, 15:17   #6
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I sailed by Newport this morning and had 53 collision warning alarms. 51 of them were docked/moored pleasure craft, while two were ships underway that were important for me to be able to follow.
Sort out your alarm and keep a proper watch.
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Old 15-05-2013, 15:22   #7
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Re: Please turn your AIS off when docked/moored/anchored

The thing is Evans was sailing by Newport and picking up all the AIS signals from all the boats in the harbor--if he set the alarm circle too tight he wouldn't pick up the commercial vessels underway out where he was. This is a result of all the superyachts tied up in Newport these days--I have been next to some of these guys who leave their radars on while tied up at the dock in harbor.
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Old 15-05-2013, 15:45   #8
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Re: Please turn your AIS off when docked/moored/anchored

It is kind of silly leaving your AIS on when at the dock, unless you are planning on leaving within 2 hours... But at anchor you should leave it on as a collision avoidance device.

I also would have turn of the collision alarm long before it reached 53 alarms... I seldom use the collision avoidance alarm on my AIS, except in reduced visibility and/or dark.
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Old 15-05-2013, 15:48   #9
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Re: Please turn your AIS off when docked/moored/anchored

One doesn't need alarm circles or even CPA/TCPA calculations - just set the AIS receiver (or chartplotter, etc) to ignore non-moving boats. This way, you can pass right through an anchorage and not set off any alarms, while moving boats still trigger the alarms. Some chart plotters and computer charting programs will even make the non-moving targets a different color than moving targets, and alarmed targets another separate color. Gives one an instant visual understanding of the surrounding situation.

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Old 15-05-2013, 15:59   #10
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Re: Please turn your AIS off when docked/moored/anchored

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One doesn't need alarm circles or even CPA/TCPA calculations - just set the AIS receiver (or chartplotter, etc) to ignore non-moving boats.
Probably a workaround, but it would also then ignore ships that were temporarily not moving, while weighing anchor and such. When entering St. John, New Brunswick, in a pea souper many years ago I was glued to the radar and saw a solid wall across the harbor that didn't appear on my charts. I called harbor control and it was a super tanker hovering there waiting for me to cut in front of his bow so he could proceed up the harbor--this was before AIS. It was rather eerie hearing his giant prop start to turn behind me: whoosh, whoosh, whoosh.
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Old 15-05-2013, 17:01   #11
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Re: Please turn your AIS off when docked/moored/anchored

Totally agree with turning off when docked or inside harbor and not soon about to leave. I got a signal last week from a fishing boat on a trailer in the parking lot!

Probably even mooring. Unless I happen to be moored on the outside of the field.
If I am a few rows in and have a good crash barrier I am okay turning it off.

Not so sure about anchored. I would likely leave it on. Even in a designated anchorage and especially if anchored in an open road-stead. I the case of an open road-stead aren't you technically underway even if anchored and not moving?
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Old 15-05-2013, 17:11   #12
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It almost never works to try to adjust the behavior of others. A far more effective approach is to figure out a way to deal with their behavior as it is.
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Old 15-05-2013, 17:17   #13
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Re: Please turn your AIS off when docked/moored/anchored

Whilst having AIS on when tucked up in a Marina berth might be a bit OTT, hanging on the hook or a mooring ball would make some sense - never know when someone is coming within range and is heavily relying on electronics.

Am not familiar with AIS, but would be surprised if cannot adjust the non-relevant vessels away as clutter (once you have identified them as such), far better you do that than a gizmo decide for ya. In any event, it is not as if every vessel will be fitted with AIS so can't ignore the window option entirely.
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Old 15-05-2013, 17:47   #14
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Re: Please turn your AIS off when docked/moored/anchored

This may turn out to be as futile a quest as eradicating aimlessly blinking turn signals on south Florida straightaways.
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Old 15-05-2013, 17:55   #15
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This may turn out to be as futile a quest as eradicating aimlessly blinking turn signals on south Florida straightaways.
Exactly. The battle is already lost. We lost the flashing green and red anchor light battle, the radars on at anchor, bells ringing in the fog, on and on. A few dozen sailors out here and a thousand noobs.
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