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Old 03-02-2015, 11:55   #46
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Re: Advice needed on AIS

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Originally Posted by barnakiel View Post

I believe now there is even an AIS/DSC MOB beacon available. Pretty fine invention for any boat sailed by a couple or other small crew.

b.

Don't know if the technology increases effectiveness or not, but the geek in me wants an AIS-DSC-MOB beacon.


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Old 03-02-2015, 12:11   #47
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Re: Advice needed on AIS

Yes I was looking at the AIS MOB device too, but its range is 4nm. I was thinking the small epirb was the better choice. BTW am I missing something? I thought the radios with GPS had an MOB button, but now I don't see them. Does Watchmate have it?
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Old 03-02-2015, 12:56   #48
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Re: Advice needed on AIS

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Basically no because it would have to have cell or WiFi connection both of which are unpredictable to no existent on anything more than a lake.(...)
Basically yes as there are services that track AIS via the satellites. This is a paid service.

Closer inland AIS data is collected and distributed by harbour and zone traffic control centers. This data is available online free of charges.

Google some more.

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Old 03-02-2015, 12:56   #49
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Re: Advice needed on AIS

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Originally Posted by Don C L View Post
Yes I was looking at the AIS MOB device too, but its range is 4nm. I was thinking the small epirb was the better choice. BTW am I missing something? I thought the radios with GPS had an MOB button, but now I don't see them. Does Watchmate have it?
If you hit the radio's DCS emergency button, it records the GPS position at that time and sends it to a chart plotter, etc if connected. It stays this way (with alarm) until it is deliberately deleted from memory. So in this way, it acts as a MOB marker - provided it is activated at the time of the MOB.

There is no need for AIS MOB devices to have a greater range. If one fell off the boat, the device immediately activates an alarm on board and sends its position - which can be navigated to. It is unlikely that a boat will get more than 4 miles away during this period.

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Old 03-02-2015, 14:04   #50
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Re: Advice needed on AIS

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If you hit the radio's DCS emergency button, it records the GPS position at that time and sends it to a chart plotter, etc if connected. It stays this way (with alarm) until it is deliberately deleted from memory. So in this way, it acts as a MOB marker - provided it is activated at the time of the MOB.

There is no need for AIS MOB devices to have a greater range. If one fell off the boat, the device immediately activates an alarm on board and sends its position - which can be navigated to. It is unlikely that a boat will get more than 4 miles away during this period.

Mark
Yeah that is true. I was thinking though, what about times when sea conditions don't permit the boat to return to the MOB. You could still broadcast their location I guess for SAR. If I am off the boat, and they aren't able to make it back to me, I would want an epirb right now! Remember the old days when cars didn't have seat belts and bike helmets were only for racers and VHF was all a boat would have? How did we survive?
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Old 03-02-2015, 21:22   #51
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Re: Advice needed on AIS

A good thing about an AIS-MOB is other boats will see you (assuming they have AIS). Not so with an EPIRB. Something to consider. Also, some AIS AtoN and base stations will relay AIS-MOB to increase their range.

One thing to note though... not all display devices know about AIS MOB's. Many just show the MOB as an unnamed vessel. This will change over time I'm sure, but that's how they were designed - so at least you show up on every display even if just as a vessel.

WatchMate's of course don't do that They immediately trigger an alarm for any AIS MOB and give you the range and bearing back.
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Old 03-02-2015, 21:33   #52
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Re: Advice needed on AIS

After sorting the AIS transceiver I also looked at MOB. Found choice between AIS beacons and DSC VHF handheld radio. The radios can be significantly cheaper as there are lots of offer.
Difference? AIS may be automatic (not all) and is picked up by the AIS receiver, broadcast its position when immersed so goes off when the life-jacket inflates.
DSC, not automatic you have to press the distress button. Received as a DSC alert with position via on-board VHF and transferred to plotter. However has in important extra that allows the on-board radio to poll the mobile which will then report its position.
The decision maker for me was that the radio allows you to talk to the MOB so they now you are coming and can get you the last 100m, much easier for a man in the water to see the boat than the other way round.

Both broadcast as 'all ships emergency' and ring alarms.
Range is similar as both are transmitting VHF however AIS max is 2w, radio is 6w
Either is a big improvement on circling round to lob a maker bouy at the casualty if you can still find them!!!!
Could not find any ref to a combined AIS/DSC I suspect this refers only to fixed station radios receiving the alerts not MOB devices transmitting from the casualty.
For a large crew the dedicated system with fobs is still the cheapest if you want all crew to have a personal device.
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Old 03-02-2015, 22:23   #53
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Re: Advice needed on AIS

Don L....lotta good advice on this thread. Like Colemj I too have the SH2150. I have mine connected to my Garmin 741XS Plotter. Really enjoy the performance of both. IMs. Claus gave me a Radar for Christmas so now to hook it up. In the future I will go with a transponder but til then I fly 2 Radar reflectors.

Previous poster stated using only "antennae that is a foot long" with his VHF. I could understand a AIS transponder antennae that length but certainly not a fixed mount VHF. If so, be on the look out for a replacement soon cause it's (VHF) about to quit on him.

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Old 04-02-2015, 04:52   #54
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Re: Advice needed on AIS

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Originally Posted by roland stockham View Post
After sorting the AIS transceiver I also looked at MOB. Found choice between AIS beacons and DSC VHF handheld radio. The radios can be significantly cheaper as there are lots of offer.
Difference? AIS may be automatic (not all) and is picked up by the AIS receiver, broadcast its position when immersed so goes off when the life-jacket inflates.
DSC, not automatic you have to press the distress button. Received as a DSC alert with position via on-board VHF and transferred to plotter. However has in important extra that allows the on-board radio to poll the mobile which will then report its position.
The decision maker for me was that the radio allows you to talk to the MOB so they now you are coming and can get you the last 100m, much easier for a man in the water to see the boat than the other way round.

Both broadcast as 'all ships emergency' and ring alarms.
Range is similar as both are transmitting VHF however AIS max is 2w, radio is 6w
Either is a big improvement on circling round to lob a maker bouy at the casualty if you can still find them!!!!
Could not find any ref to a combined AIS/DSC I suspect this refers only to fixed station radios receiving the alerts not MOB devices transmitting from the casualty.
For a large crew the dedicated system with fobs is still the cheapest if you want all crew to have a personal device.

IN my view AIS SART is superior as there is a specific agreement on MOB alarms, which now show as such on chart plotters. using DSC, could be mistaken for a SHIP in distress and cause an incorrect rescue response, There is also the issue of cancelling these distress acknowledgements. To my understanding there is no international agreement on the use of DSC for MOB. ( i.e. the distress signal is emanating from the MOB).

In temperate waters , I have in the past seriously questioned the value of EPIRBS for MOB protection
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Old 04-02-2015, 05:21   #55
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Re: Advice needed on AIS

I need some advice , before an Atlantic crossing ( possibly singlehanded ) -
I am looking to fit Radar any suggestions on the best make or brand and power consumption and are they worth the cost.
Looking at the threads it seems that AIS send/receive might be a better option ,again suggestions as to the best brand and the power consumption.
Any help with type ,mounting ,screens ,power etc would be a great help.
Cheers G.
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Old 04-02-2015, 05:28   #56
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Re: Advice needed on AIS

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I need some advice , before an Atlantic crossing ( possibly singlehanded ) -
I am looking to fit Radar any suggestions on the best make or brand and power consumption and are they worth the cost.
Looking at the threads it seems that AIS send/receive might be a better option ,again suggestions as to the best brand and the power consumption.
Any help with type ,mounting ,screens ,power etc would be a great help.
Cheers G.
This has been debated several times, but AIS and Radar are fundamentally different have advantages in being used together or separately.

If you have the budget, buy a radar, if you are very tight on budget get an AIS, preferably a transponder. If you can get both. When you need them both are very useful devices on board.

I would even suggest that its better to compromise the quality and power of the radar and buy both units, even if the radar is not the ghee-whizz version.

In reality on a small boat , you do not need a powerful or sophisticated radar , but its very handy to have some form of radar

comparing AIS and radar is like comparing VHF and radar

dave
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Old 04-02-2015, 09:08   #57
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Re: Advice needed on AIS

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Originally Posted by goboatingnow View Post
IN my view AIS SART is superior as there is a specific agreement on MOB alarms, which now show as such on chart plotters. using DSC, could be mistaken for a SHIP in distress and cause an incorrect rescue response, There is also the issue of cancelling these distress acknowledgements. To my understanding there is no international agreement on the use of DSC for MOB. ( i.e. the distress signal is emanating from the MOB).

In temperate waters , I have in the past seriously questioned the value of EPIRBS for MOB protection
You make good points. There is a distress category for MOB but not sure if you can set it as a default so the casualty, unless very clear headed, is likly to just send an undesignated distress call. Any third party however will be in voice comm's with both the ship and the casualty so situation can quickly be clarified by the designated controller. Remember this is all at ranges where ships will be in visual contact.
I am primarily looging at it for when I have one person on watch during passages

Agree with you about EPIRB for MOB although it may be possible to get a position relayed from the coast guard controller if you have SSB
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Old 04-02-2015, 09:13   #58
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Re: Advice needed on AIS

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Originally Posted by roland stockham View Post
You make good points. There is a distress category for MOB but not sure if you can set it as a default so the casualty, unless very clear headed, is likly to just send an undesignated distress call. Any third party however will be in voice comm's with both the ship and the casualty so situation can quickly be clarified by the designated controller. Remember this is all at ranges where ships will be in visual contact.
I am primarily looging at it for when I have one person on watch during passages

Agree with you about EPIRB for MOB although it may be possible to get a position relayed from the coast guard controller if you have SSB

There are actually more issues then you have alluded to.

The first is the primary recipient of a DSC distress is the shore erased coastguard infrastructure, not other ships, under GMDSS, ships are actually suppose to wait for a CG response before getting involved. If the CG cannot raise the MOB for whatever reason, then a rescue asset can and is often dispatched.

Futhermore, many ships will on not hearing a CG voice response, follow the recommended procedure, enacting a MAYDAY relay. Again with confusing responses and the MMSI will indicate that it is a VESSEL in distress.

AIS SART on the other hand has a specific code for MOB. And AIS will not in itself begin a rescue alert.

It gets even worse if a ship relays a VHF DSC via HF etc etc.
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Old 04-02-2015, 09:14   #59
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Re: Advice needed on AIS

Quote:
Originally Posted by GarthGregory View Post
I need some advice , before an Atlantic crossing ( possibly singlehanded ) -
I am looking to fit Radar any suggestions on the best make or brand and power consumption and are they worth the cost.
Looking at the threads it seems that AIS send/receive might be a better option ,again suggestions as to the best brand and the power consumption.
Any help with type ,mounting ,screens ,power etc would be a great help.
Cheers G.
Whatever you fit it is essential to have a heading sensor/compass input that stabilizes it otherwise the image swings around so much it is impossible to read. In the trades I found it very useful for seeing squalls at night, gives you time to reef
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Old 04-02-2015, 09:16   #60
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Re: Advice needed on AIS

At 6 knots versus their 20+ knots, they are in a much better situation than you are to avoid a collision Basically, it is much easier for them to create a minimum CPA than for you to create that same CPA. If they can see you on AIS rather than just you seeing them on AIS, then you are much better off.

Also, don't be shy about getting on the radio to first confirm if they can see you on radar and then to confirm a passing arrangement.
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