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Old 15-04-2019, 14:03   #1
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AIS Military vessel alarm

So I installed my new icom M506 and itís working fantastically. I seem to do a lot of overnight solo passages and this unit allows to grab some cat naps. Before the new AIS I would just not sleep, I would rest but not sleep.

Anyway sailing south from Nassau the other day when the watch alarm went off I dashed up the companion way and to my surprise there was a large vessel heading straight for me...! So went down below and checked the AIS screen and sure enough ĎRangerí a militarily vessel with a CPA of 0.0kn was showing on the screen but no audible or visual alarm. The AIS has been working flawlessly before and after this event. P.s. the vessel did give way to me in good time in a professional manner. Is this a military thing or a glitch?

Regards Steven
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Old 16-04-2019, 04:48   #2
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Re: AIS Military vessel alarm

That unit appears to be AIS receiver only, so you could see “ranger” but they could not see you on the AIS (good chance they saw you on radar, and came to have a look and see if you were a drug runner etc)

If you want others to be able to see you on AIS, you need a transceiver (transponder), not just a receive only built into a radio. Using it as an aid to sleep may not be the best idea - it can only see other vessels that have transponders - if another single hander is set up the same as you, and not keeping watch like you, trying to occupy the same piece of water, you gonna crash.....
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Old 16-04-2019, 05:16   #3
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Re: AIS Military vessel alarm

I think he is asking about his alarm not sounding?
If so, then no that is not a Military thing, that would be your device.

I would NOT rely on AIS to provide warning so I could cat nap. It seems to me that many fishing vessels fish with their AIS off, assumption is they donít want others to know if they are on fish, but they are a hazard with the AIS off and of course even if your sailing, they are the stand to vessel, so they may not maneuver to avoid collision, and or may not be able to if they are dragging a net.
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Old 16-04-2019, 05:40   #4
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Re: AIS Military vessel alarm

AIS transmission requirement does not apply to military ships, and US government ships are explicitly exempted in the USCG regulations, as I guess other people's navies are for security reasons. ß 164.01 Applicability (c) : https://www.navcen.uscg.gov/?pageNam...equirementsRev (c) Provisions of ßß 164.11(a)(2) and (c), 164.30, 164.33, and 164.46 do not apply to warships or other vessels owned, leased, or operated by the United States Government and used only in government noncommercial service when these vessels are equipped with electronic navigation systems that have met the applicable agency regulations regarding navigation safety.

Following the McCain and Fitzgerald accidents in 2017, the Chief of Naval Operations ordered that USN ships begin transmitting AIS when in heavily congested areas: https://news.usni.org/2017/09/19/dea...-traffic-areas

Not sure about other navies, or who you wandered across, but it seems to reason that they saw you long before you saw them. Probably they switched on the AIS at the last minute when they figured out that you were not a bad guy, to warn you off.
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Old 16-04-2019, 09:17   #5
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Re: AIS Military vessel alarm

same in Canada
i have run across military ships that do not transmit
sometime in the worst of places
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Old 16-04-2019, 09:23   #6
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Re: AIS Military vessel alarm

Naval and paramilitary vessels don't transmit for understandable strategic reasons, i.e. why give a foe a target?
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Old 16-04-2019, 10:08   #7
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Re: AIS Military vessel alarm

All where I have sailed military/government vessels do not transmit AIS signals. This is the normal state as they want to be able to come close to you with minimal notice.
However, they do have transmitters that may be switched on when they find it useful.
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Old 16-04-2019, 10:22   #8
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Re: AIS Military vessel alarm

In The South Chinese Sea the military vessels are often transmitting AIS, but normally with funny MMSI numbers...
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Old 16-04-2019, 10:33   #9
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Re: AIS Military vessel alarm

It seems to me based on my study of solo sailing, (I hope to do some in the future) that the best time for a solo sailor to get sleep is in the daytime when your vessel is most visible to others and hazards are most visible to you.

Do you choose to rely on the nav equipment during your naps at night because that is when your accustomed to sleeping and have to sleep?
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Old 16-04-2019, 11:15   #10
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Re: AIS Military vessel alarm

Quote:
Originally Posted by BenBowSirocco View Post
It seems to me based on my study of solo sailing, (I hope to do some in the future) that the best time for a solo sailor to get sleep is in the daytime when your vessel is most visible to others and hazards are most visible to you.

Do you choose to rely on the nav equipment during your naps at night because that is when your accustomed to sleeping and have to sleep?
Human beings are not nocturnal animals - we are genetically programmed to sleep when it gets dark. Shift workers, and people who live at high polar latitudes suffer various ailments when they have to be awake when it is dark.

As you say, your knowledge of single handing is from study, not actually doing.
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Old 16-04-2019, 12:01   #11
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Re: AIS Military vessel alarm

In the Western Med, we've come across a convoy of ships travelling totally dark and without transmitting on AIS. They were clear as day on radar, and when they passed in the reflection of the moon, were clearly military vessels. My wife was on watch and called me up when AIS only showed one thing - an AIS contact (designation "SAR") travelling head on towards us at 130kts! She of course freaked out. It was a plane checking us out, no doubt doing a threat assessment for the fleet.

We've seen lots of "NATO warship" designations on AIS, but sometimes military will travel not only without AIS, but without any running lights.
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Old 16-04-2019, 12:10   #12
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Re: AIS Military vessel alarm

US military vessels do not run their AIS equipment in transmit mode when operating on the open sea for obvious reasons.
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Old 16-04-2019, 12:27   #13
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Re: AIS Military vessel alarm

Iíve never heard of an aircraft transmitting AIS, itís possible of course, but wonder why one would?
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Old 16-04-2019, 12:36   #14
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Re: AIS Military vessel alarm

All the Search and Rescue helicopters here in Ireland transmit AIS.
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Old 16-04-2019, 12:43   #15
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Re: AIS Military vessel alarm

130 knots is in the ballpark for a helo.
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