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Thread: A.I.S

  1. #1
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    Default A.I.S

    I'm out of the cruising threads because apparently 'real cruisers' don't use modern technology or sail anything bigger than 12 ft long. They only use sextants and paper charts and just crash on up to nations quite prepared to arrest you and impound your boat if you don't follow the rules of advance notice, etc.

    But here's one little example of AIS in action nearly this time last year , albeit after the excitement.
    500 miles south of Fiji, about 500 from home thereabouts..





    I didn't want to go behind it because , well, you just don't know what they have out the back. We never did get a response but all the calls we made must have at least got their attention eventually , because they did alter course to go behind us, which we appreciated.

  2. #2
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    Default Re: A.I.S

    Our particular unit is also free standing below in that it has its own screen. The anchor watch function is really useful in a blow because I can read it from the bunk. It has the usual alarm, but a collateral advantage is being able to see where the boat has been... we used this one to unwind from a rock


  3. #3
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    Default Re: A.I.S

    I fitted one for our trip from Hobart to Adelaide, but in the usual rush of things failed to get it sorted before we left. Bruce's nephew Matt got it sorted for me a few months ago, and now from our berth at North Haven we can see who is coming and going all over the Gulf and Port Adelaide. Very neat.

  4. #4
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    Default Re: A.I.S

    I don't have a sextant though.

  5. #5
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    Default Re: A.I.S

    I've fitted an AIS transceiver to Meg. It's integrated with the GPS display. Can't wait to start playing with it.

    I am one of those who does a DR plot first, then visual bearings if visibility allows, then GPS. I do this a great deal in fair weather and in waters I know well, could easily sail from memory. It's all about keeping all skills sharp and related. Then if conditions cause one' or two to be out, I'm still good.

    The AIS is far better than a radar reflector at both alerting commercial or other AID equipped vessels of your presence and presents you with information far less confusing and ambiguous than radar as to what's headed your way.

    There is nothing wrong with choosing traditional methods any more than there's nothing wrong with sailing a plank on frame boat. What's wrong is to feel that by so doing one is morally superior.

    The other side of this coin is, of course, the weekend warrior who treats going to sea as a video game. Such nautical hazards are beneath contempt.

  6. #6
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    Default Re: A.I.S

    Brilliant tech !!!
    '' You ain't gonna learn what you don't want to know. ''
    Grateful Dead

  7. #7
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    Default Re: A.I.S

    I was gob-smacked to hear that rigs don't fit them. Granted the radar signature is huge, but the risk of a ship collision with 500 BarG of natural gas flowing is what everyone fears most while aboard. I would have thought the cost / risk value of such a system would be worth it, considering what a tired officer on the bridge of a large ship can misinterpret on his / her radar screen in heavy weather.

  8. #8
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    Default Re: A.I.S

    We installed an AIS-equipped VHF radio a couple of years ago. Oddly, the radio was less expensive than an independent AIS receiver alone. The AIS option added about $100 to the radio cost. The radio can transmit your own GPS coordinates at the push of a button, but doesn't transmit constantly, as a transceiver does. It displays all the vessels in the area broadcasting AIS--which is all the commercial traffic. It still calculates a collision course within line-of-sight range, which can be set to sound an alarm. All in all it's the most effective anti-collision device I've seen, not the mention the lowest cost.

  9. #9
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    Default Re: A.I.S

    ^ Sounds good.

    I'm going for a dedicated AIS transponder on Kate; I'd like others to see me.

  10. #10
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    Default Re: A.I.S

    Quote Originally Posted by lupussonic View Post
    ^ Sounds good.

    I'm going for a dedicated AIS transponder on Kate; I'd like others to see me.
    The system is basically just sending and receiving a vessel's GPS data on a dedicated VHF channel. I don't know why all of them aren't transceivers. The radio I bought does send out the GPS, but you have to hit a button to do it manually. I would not be surprised if eventually they add an automatic transceiver to the system, since all the electronics are there already. Might note that the radio is self-contained, includes a GPS unit, a tiny screen display, and built-in GPS antenna. A mast-mounted VHF antenna completes the system. The data goes to a separate computer display as well, which includes a chart plotter.

  11. #11
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    Default Re: A.I.S

    All those those 12' cruisers can load a marine traffic app on their phones so they don't get run over. https://www.westmarine.com/WestAdvis...raffic-AIS-App

  12. #12
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    Default Re: A.I.S

    My experience with ancillary screens or devices is there's an issue ensuring they're charged enough when you want them. For something that needs to be on 24/7 to be of value that isn't really good enough. It can be done of course and we do have the apps that pick up the AIS data from our vesper, but that would be mostly for a periodic check on off, for convenience.
    I also found that even plugged in, some programs or apps use more power than what is going in, so management of the things becomes another task. Google earth on an ipad for example, is power hungry, especially since you have the screen on max for daytime nav through the reefs.
    So they're great, with issues, and that makes them useful for backup and specialised shorter time tasks. No substitute for a proper unit wired in.

  13. #13
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    Default Re: A.I.S

    I have just circumnavigated Britain on a boat equipped with an AIS transceiver and with AIS info displayed on the chart plotter. Despite being inherently sceptical of high tech gizmos (more to go wrong, dependency culture,etc), I was sold from the moment when we were crossing Belfast Lough in thick fog and were plotting the progress of a Dutch tanker and its CPA on both radar and the plotter (AIS) _ only to have them call us up to confirm whether we were sailing or under power and to tell us that they were altering Couse to pass astern.
    They passed about half a mile astern; we could hear them clearly but saw nothing !
    Nick

  14. #14
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    Default Re: A.I.S

    My experience with ancillary screens or devices is there's an issue ensuring they're charged enough when you want them. For something that needs to be on 24/7 to be of value that isn't really good enough. It can be done of course and we do have the apps that pick up the AIS data from our vesper, but that would be mostly for a periodic check on off, for convenience.
    I also found that even plugged in, some programs or apps use more power than what is going in, so management of the things becomes another task. Google earth on an ipad for example, is power hungry, especially since you have the screen on max for daytime nav through the reefs.
    So they're great, with issues, and that makes them useful for backup and specialised shorter time tasks. No substitute for a proper unit wired in.
    Spot on.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  15. #15
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    Default Re: A.I.S

    Quote Originally Posted by John B View Post
    My experience with ancillary screens or devices is there's an issue ensuring they're charged enough when you want them. For something that needs to be on 24/7 to be of value that isn't really good enough. It can be done of course and we do have the apps that pick up the AIS data from our vesper, but that would be mostly for a periodic check on off, for convenience.
    I also found that even plugged in, some programs or apps use more power than what is going in, so management of the things becomes another task. Google earth on an ipad for example, is power hungry, especially since you have the screen on max for daytime nav through the reefs.
    So they're great, with issues, and that makes them useful for backup and specialised shorter time tasks. No substitute for a proper unit wired in.
    The GME AIS transceiver I've bought but still haven't installed, has no screen so I'm supposed to link it to the chartplotter. I wonder if that'll be an issue?

    Rick

  16. #16
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    Default Re: A.I.S

    AIS and Radar are of course two different animals and cannot be compared directly. But I’m a bit concerned with those who say AIS is better at collision avoidance than radar. Radar sees everything, AIS receivers only see who is transmitting. My house has a view of the shipping lanes and I am amazed at the number of vessels supposedly required to transmit, don’t. Many are just scofflaws . But also military vessels do not transmit so a 1000’ carrier will show up pretty well on radar, but AIS not at all. And tug and barges may be several hundred feet long, but the tug may be too small to require AIS and even if they do, the barge doesn’t. If I could only have one, it would be radar.

  17. #17
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    Default Re: A.I.S

    Both are probably best, but AIS is so cheap, a receiver at any rate, why wouldn't you have one? Just dont trust it to see everything, obviously. When I had radar, by the time i had it tuned to cut out clutter and just show real targets, I could usually see the vessel before radar picked it up. Handy to know the vessels heading and speed, but otherwise the Mk 1 eyeball was pretty much as good. No fog of course.

  18. #18
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    Default Re: A.I.S

    Radar sees everything,
    No, it doesn't.

    Radar cannot see the vessel behind the ship in front of you, the vessel running between the jetties at low tide, the vessel around the other side of a point of land, etc. AIS can " see," all of those, to the extent the VHF signal isn't blocked.

    AIS, as you say, only shows vessels so equipped. That means most commercial vessels, but just a small percentage of recreational vessels.

    Radar can show you the navaids, the seawall, the mooring bouys, the shoreline, all of which AIS is blind to. Radar will show you a flock of birds indicating ( possibly) feeding fish. Radar can show thunderstorms.

    AIS lets you know at a glance what the target is, what its name is so you can hail it. With Radar you have to guess the target's identity in many instances.

    If I could only have one, it would be radar.
    Me, too.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  19. #19
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    Default Re: A.I.S

    As a watch officer on a large ship, I really appreciate those pleasure craft and fishing vessels that transmit AIS. You don't show up on radar until fairly close, even with reflectors.

    Do take the information received with a grain of salt though. As mentioned before Military ships rarely transmit, and many ships send bad information. I regularly see the AIS targets at a different location than my radar shows them. And the vessel status may be wrong, especially just after arriving or departing. We do look at all the detailed information sent. There are many things to do at the same time, and updating the AIS may take some time to get to, and even forgotten about. There's nothing like a ship "At Anchor" moving at 12 kts in the fairway. Make sure you update your underway information. We have that on our checklist to make sure we don't forget.

  20. #20
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    Default Re: A.I.S

    Quote Originally Posted by captsct View Post
    As a watch officer on a large ship, I really appreciate those pleasure craft and fishing vessels that transmit AIS. You don't show up on radar until fairly close, even with reflectors.
    Interesting to me that you say this. In my cruising grounds, San Francisco Bay and the Sacramento Delta, all the big ships are in the shipping lanes and on a schedule. Often they are accompanied by tugs, always it would be difficult for them to change course and impossible to stop quickly. I figure it is my job to stay out of their way, crossing shipping lanes only when I can see it's clear. I would also assume that any AIS from a pleasure boat is just clutter, I mean what is the skipper going to do if he sees an AIS from a sailboat right in front of him? I feel like I'm a rabbit on the side of the road, and you guys are the trucks on the interstate.
    As an example, this was the Lime Galaxy in the deepwater channel. We just pulled over until she passed.


  21. #21
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    Default Re: A.I.S

    DR plot AND brearings BEFORE GPS, even with local knowledge, Ian? Wow, Just learned how to do that stuff in our Power Squadrons Piloting and Advanced Piloting classes. For decades I've just oriented my chart, quickly determined an approximate course toward my destination, and looked over the side to check for rocks. The courses have had the effect to impress me just what a chart plotter could do for us before we plan another cruise in tidal waters.

  22. #22
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    Default Re: A.I.S

    I helped deliver a boat to Ensenada in October. We had GPS, AIS and radar all on the same screen, lovely, made finding position and getting into anchorages dead simple, even at night in fog. However we almost T boned an approaching coastguard ship in broad daylight when the skipper, down below, made a 45 degree course change on the autopilot because AIS told him we would collide with another boat in 5 or 10 minutes. I guess he'd forgotten that not everyone is transmitting.

    Not sure if there's a moral here, maybe to not ignore the real world in favour of tech?

    BTW, the skipper stayed below, leaving me to give the CG an embarrassed wave as we passed each other.

    Jamie

  23. #23
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    Default Re: A.I.S

    I would be reluctant to sail offshore single handed again without an AIS receiver. Radar can consume too many amps for small sailboats. The "guard zone" is just that little bit of extra security that can let you know something is getting close enough to worry about. I guess a transponder unit would be more benefit also, as long as others are paying attention. The combined unit on the Standard Horizon VHF, seems excellent value for a warning device, though granted a dedicated display would be easier to read.

  24. #24
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    Default Re: A.I.S

    Quote Originally Posted by Jamie Orr View Post
    I helped deliver a boat to Ensenada in October. We had GPS, AIS and radar all on the same screen, lovely, made finding position and getting into anchorages dead simple, even at night in fog. However we almost T boned an approaching coastguard ship in broad daylight when the skipper, down below, made a 45 degree course change on the autopilot because AIS told him we would collide with another boat in 5 or 10 minutes. I guess he'd forgotten that not everyone is transmitting.

    Not sure if there's a moral here, maybe to not ignore the real world in favour of tech?

    BTW, the skipper stayed below, leaving me to give the CG an embarrassed wave as we passed each other.

    Jamie
    One moral, the navigator should look out of the windows.
    Bigger moral. Officialdom should turn their AIS on, unless there is a damned good operational reason for cloaking. Remember those two collisions with fatalities in the far east?
    It really is quite difficult to build an ugly wooden boat.

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  25. #25
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    Default Re: A.I.S

    Sailing in warships, I abhor that we transmit on AIS. As a mariner, it's a godsend. I had the idea once of setting up each ship with a RACON type transponder that could transmit a code showing what ship was which. Simple and crude compared to what eventually came to be AIS. This was back in my merchant mariner days on the great lakes. I never pursued the idea, mentioning it only to one of the watch officers I was working with at the time. I should have given it more thought and pursued it. I might be rich by now. Then one day a few years later, one of our ships deployed and the captain used some of his operational budget to buy one of these newfangled AIS thingamabobs. By the time he returned from his deployment, our entire navy had them. They work RMP miracles. The problem with them from a warship's perspective is simply hiding. Anything big enough to be a warship (us) has to transmit. if it doesn't, there's something suspicious about her. So... if we don't transmit, we stand out. If we transmit our true name etc. we are known to be a warship and cannot hide. If we transmit fake data, it's easy to see that we're spoofing it and we're given up so there's no way to hide if a warship wants to hide. On the other side of that coin, the bad guys can't hide either if they're over the minimum size to carry an AIS transponder.
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  26. #26
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    Default Re: A.I.S

    Quote Originally Posted by Sailor View Post
    Sailing in warships, I abhor that we transmit on AIS. As a mariner, it's a godsend. I had the idea once of setting up each ship with a RACON type transponder that could transmit a code showing what ship was which. Simple and crude compared to what eventually came to be AIS. This was back in my merchant mariner days on the great lakes. I never pursued the idea, mentioning it only to one of the watch officers I was working with at the time. I should have given it more thought and pursued it. I might be rich by now. Then one day a few years later, one of our ships deployed and the captain used some of his operational budget to buy one of these newfangled AIS thingamabobs. By the time he returned from his deployment, our entire navy had them. They work RMP miracles. The problem with them from a warship's perspective is simply hiding. Anything big enough to be a warship (us) has to transmit. if it doesn't, there's something suspicious about her. So... if we don't transmit, we stand out. If we transmit our true name etc. we are known to be a warship and cannot hide. If we transmit fake data, it's easy to see that we're spoofing it and we're given up so there's no way to hide if a warship wants to hide. On the other side of that coin, the bad guys can't hide either if they're over the minimum size to carry an AIS transponder.
    Why would any warship/coast guard cutter need to hide when bimbling about on passage from A to B? Same applies to any activity when there is not a war on, or not looking for criminal activity. I am sure that the families of those crew men killed in those two collisions will have a view on that.
    It really is quite difficult to build an ugly wooden boat.

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  27. #27
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    Default Re: A.I.S

    Friend of mine got hit in the Atlantic by a large reefer. He lost his boat due to the damage. He did not realise that a simple AIS could run off his limited, solar powered electrics, if he had, he would have fitted one.
    Another friend, more recently, had to call a ship that was coming up behind fast in mid Atlantic. There was no signal on their AIS and the guy on watch hadn't seen it. The ship said they were aware and suddenly changed course, but if they had been, they would have changed far sooner. Friend's boat only had passive AIS, as power limited, but they did have a decent radar reflector.

    Edit:
    As for warships, one would like to think they a/ have the sort of radar that could spot a wooden dinghy at several miles and b/ a few people actually on watch looking out.
    Last edited by Andrew2; 12-26-2018 at 06:57 AM.

  28. #28
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    Default Re: A.I.S

    Quote Originally Posted by Andrew2 View Post


    Edit:
    As for warships, one would like to think they a/ have the sort of radar that could spot a wooden dinghy at several miles and b/ a few people actually on watch looking out.
    Trouble with that is fog or confusion caused by too many vessels in a shipping lane along a well lit coast at night.
    It really is quite difficult to build an ugly wooden boat.

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  29. #29
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    Default Re: A.I.S

    Quote Originally Posted by Peerie Maa View Post
    Trouble with that is fog or confusion caused by too many vessels in a shipping lane along a well lit coast at night.
    I was thinking that at least the grey funnel jobs could avoid peeps that were not aware of them, rather than us avoiding them.

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