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Old 17-12-2018, 14:28   #76
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Re: "A" versus "B" AIS - worth transmitting?

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Originally Posted by dmkkeng View Post
The short answer is yes - here are my thoughts on AIS. I debated the same thing when I first started to look into AIS. Class A (receive only) is easier to install and cost less so my first thought was just install a Class A system. In terms of collision avoidance it only allows you to use the system to make course changes. With a Class B system it provides the potential for everyone with AIS capability to make course changes or at least provide notification in the scenario where they cannot make course changes. To get the full benefit of AIS you need a Class B (transmit & receive) system. Most Class B systems have the option of disabling transmit if you are inclined to do so. I have yet to do so. I do however shut my AIS system off while at dock - at times it can be difficult to differentiate someone who is at dock or is just leaving dock. I think it prudent for users of AIS systems to shut their system off while at dock as the main purpose for AIS is collision avoidance. I have disabled the audible alarm on my AIS for this reason, however my AIS system is integrated with my other navigation systems and a single display. Someone is always at the helm to see what is happening visually. From a sailing perspective I used it to make course changes well in advance of any collision, often the boat that I am on the collision course with will do the same. Usually I can make minor course changes to avoid the collision which often allows me to stay on the same tack and head in the same direction. Prior to having AIS I either made unnecessary course changes or waited to long and had to make drastic changes in course to avoid a collision. AIS definitely improves sailing efficiency.


A is high power commercial
B is low power recreational

Receivers are neither A nor B.
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Old 17-12-2018, 18:56   #77
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Re: "A" versus "B" AIS - worth transmitting?

Fit a class B transceiver they are fabulous. Watching large commercial ships alter course 2 deg at 10miles out to give you plenty of sea room is very reassuring. But don't then assume everyone has seen you and abandon watch keeping.
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Old 17-12-2018, 20:00   #78
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Re: "A" versus "B" AIS - worth transmitting?

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. In my experience, 90% of ships will happily comply with a polite request for a small alteration in course due to some circumstance like having a chute up, or being hard on the wind, or whatever, so long as they are not in traffic or in a TSS or otherwise subject to constraints of their own. They ask each other for such favors all the time.
We must live on different planets: Never heard such a request:

Eastbound container ship 10 miles North of Big Harbor: This is little sailboat Southbound and 2 miles North on your Port Bow: Please alter course to avoid collision because I have my sails up and I have the right of way.
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Old 17-12-2018, 20:44   #79
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Re: "A" versus "B" AIS - worth transmitting?

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Originally Posted by MartinR View Post
A sailing boat is by its nature restricted in ability to change course. That is inherent in the designation. Also, a sailing boat has right of way. So what would be gained by hoisting signals and changing AIS designation to "restricted". Commercial vessels are also sometimes restricted in their ability to manoeuvre, for example in heavy weather. That does not mean we see us as "restricted" under regulations.

Normally commercial vessels do not check the status of other vessels on AIS. They do this by looking out the windows. A dredger is a dredger, a sailing boat is a sailing boat. Very clear on how to proceed. AIS does not come into the decision making here, and actually very seldom in any case. For collision avoidance we use ARPA. Small sailing boats are helped by AIS, they show up in a seaway on AIS, but often not on RADAR.
We have already beaten this subject to death, and it's off topic: it doesn't relate to ""A" versus "B" AIS - worth transmitting? "

Call your Coast Guard office and ask them about using RAM in an emergency. I did.

NUC isn't appropriate if you are still in command of the vessel. I'd use NUC only if my rudder fell off, before I passed out from exhaustion, or just before I jumped in the life raft.

If there was a more specific designation, like: "Due to extraordinary sea state conditions, this vessel is restricted to only a very small range of courses," I'd use that instead. Or better: "Don't ask me to get out of your way because I'm just trying to stay alive!"

RAM is as close as the available designations allow . I suspect most of the dissenters here have never been in 30 foot swells single-handed in a 26 foot sailboat. Most would be calling for rescue instead.
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Old 17-12-2018, 21:33   #80
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Re: "A" versus "B" AIS - worth transmitting?

... And if anyone thinks I'm exaggerating about swell sizes around here, we have 50 foot waves right now just outside my harbor. https://abc7news.com/sports/surfers-...ition/4918526/


I'm not crazy enough to go out in that, but sometimes a person gets caught out in 20 to 30 foot swells tens of miles to seaward.
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Old 17-12-2018, 22:07   #81
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Re: "A" versus "B" AIS - worth transmitting?

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Originally Posted by CSY Man View Post
We must live on different planets: Never heard such a request:

Eastbound container ship 10 miles North of Big Harbor: This is little sailboat Southbound and 2 miles North on your Port Bow: Please alter course to avoid collision because I have my sails up and I have the right of way.

I first fitted AIS in the Caribbean. Left Aruba bound for Colon and the canal. Spent the next few days keeping an eye on the AIS display and saw numerous large commercial vessels make small course alteration when about 10 miles away so as to maintain 1.5-2m CPA. Did not have to ask and it may be that they had previously done the same if they saw me on radar but I would not have known. It was great to see and we never got within close quarters radius of anything until entering harbour. I my experience commercial shipping is polite, considerate and always ready to lend a hand if asked.
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Old 18-12-2018, 00:16   #82
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Re: "A" versus "B" AIS - worth transmitting?

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Originally Posted by CSY Man View Post
We must live on different planets: Never heard such a request:

Eastbound container ship 10 miles North of Big Harbor: This is little sailboat Southbound and 2 miles North on your Port Bow: Please alter course to avoid collision because I have my sails up and I have the right of way.

We do live on different planets. On my planet no such lubberly request would be made.


Rather:


MV Titan, MV Titan [calling by name because we have AIS, not indeed "Eastbound container ship"], this is SV Dolphin SV Dolphin, over.


SV Dolphin, this is MV Titan


Zero Nine?


Going to Zero Nine.


Titan, Dolphin. Good afternoon, sir. We are the sailing vessel 10 miles off your starboard bow on course 070. We make our CPA with you 5 cables and cannot alter course to port because we are hard on the wind, and tacking would take us into the TSS. Would you be so kind as to alter a few degrees to port so that we can pass behind you? Over.


Dolphin, Titan. I'm altering my course to port. Maintain your course and speed. Over.


Titan, Dolphin. Many thanks. Good watch. Dolphin going back to one six.


Click click.




Note:


1. Nobody ever talks about who is stand on and who is give way (and for God's sake no bloody "right of way"). Nobody cares because we are making special passing arrangements in any case. Don't insult the intelligence of another mariner by lecturing him about the COLREGs.



2. Nobody says "to avoid collision". What is that about? What a silly waste of airtime.



3. Request made in good time -- 10 miles out.


4. Ship identified by name.


5. What you want is formulated as a polite request, and what you want the ship to do is stated succinctly and clearly.




I have had dozens of conversations like that, and listened to probably hundreds. The only time anyone ever refused was because of other traffic, and we simply agreed on a different way to deal with the situation.
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Old 18-12-2018, 00:25   #83
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Re: "A" versus "B" AIS - worth transmitting?

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Originally Posted by Cpt Pat View Post
. . . NUC isn't appropriate if you are still in command of the vessel. I'd use NUC only if my rudder fell off, before I passed out from exhaustion, or just before I jumped in the life raft.

If there was a more specific designation, like: "Due to extraordinary sea state conditions, this vessel is restricted to only a very small range of courses," I'd use that instead. Or better: "Don't ask me to get out of your way because I'm just trying to stay alive!"

RAM is as close as the available designations allow . I suspect most of the dissenters here have never been in 30 foot swells single-handed in a 26 foot sailboat. Most would be calling for rescue instead.

I have been in a bad storm in the North Sea some years ago which knocked down my 54' vessel. The waves were huge and steep (North Sea) and we had to pick our way carefully down the faces of the waves to avoid getting knocked down again, which means we really had no choice about the direction we could travel in. We managed several hours of that, but then we ended up in traffic lanes and in fact going the wrong way up a busy TSS, just as night fell.


There is no status for this situation -- it is not NUC and not RAM, and declaring one of those would not communicate anything useful, but merely create confusion. Anyway even if we had had shapes or lights for NUC or RAM, they would hardly have been seen in those mountainous waves with the air full of spray.



Instead we notified the Dutch Coast Guard, and then put out a Securite call informing traffic about what we were doing. Then we called every ship as it came down the TSS towards us -- some of them struggling themselves in the bad weather -- explained why we were going the wrong way in the TSS, and agreed how we would pass. In the end we got through it fine. We got a lee from the Frisian Islands and maneuvered out of the TSS and into sheltered waters, and carried on towards Helgoland, with nice weather and a beautiful sail the next morning.
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Old 18-12-2018, 01:58   #84
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Re: "A" versus "B" AIS - worth transmitting?

Quote:
Originally Posted by Dockhead View Post
We do live on different planets. On my planet no such lubberly request would be made.


Rather:


MV Titan, MV Titan [calling by name because we have AIS, not indeed "Eastbound container ship"], this is SV Dolphin SV Dolphin, over.


SV Dolphin, this is MV Titan


Zero Nine?


Going to Zero Nine.


Titan, Dolphin. Good afternoon, sir. We are the sailing vessel 10 miles off your starboard bow on course 070. We make our CPA with you 5 cables and cannot alter course to port because we are hard on the wind, and tacking would take us into the TSS. Would you be so kind as to alter a few degrees to port so that we can pass behind you? Over.


Dolphin, Titan. I'm altering my course to port. Maintain your course and speed. Over.


Titan, Dolphin. Many thanks. Good watch. Dolphin going back to one six.


Click click.




Note:


1. Nobody ever talks about who is stand on and who is give way (and for God's sake no bloody "right of way"). Nobody cares because we are making special passing arrangements in any case. Don't insult the intelligence of another mariner by lecturing him about the COLREGs.



2. Nobody says "to avoid collision". What is that about? What a silly waste of airtime.



3. Request made in good time -- 10 miles out.


4. Ship identified by name.


5. What you want is formulated as a polite request, and what you want the ship to do is stated succinctly and clearly.




I have had dozens of conversations like that, and listened to probably hundreds. The only time anyone ever refused was because of other traffic, and we simply agreed on a different way to deal with the situation.
> Don't insult the intelligence of another mariner by lecturing him about the COLREGs.


I agree. I believe we have more lawyers than sailors here.
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Old 18-12-2018, 01:59   #85
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Re: "A" versus "B" AIS - worth transmitting?

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Originally Posted by Dockhead View Post
I have been in a bad storm in the North Sea some years ago which knocked down my 54' vessel. The waves were huge and steep (North Sea) and we had to pick our way carefully down the faces of the waves to avoid getting knocked down again, which means we really had no choice about the direction we could travel in. We managed several hours of that, but then we ended up in traffic lanes and in fact going the wrong way up a busy TSS, just as night fell.


There is no status for this situation -- it is not NUC and not RAM, and declaring one of those would not communicate anything useful, but merely create confusion. Anyway even if we had had shapes or lights for NUC or RAM, they would hardly have been seen in those mountainous waves with the air full of spray.



Instead we notified the Dutch Coast Guard, and then put out a Securite call informing traffic about what we were doing. Then we called every ship as it came down the TSS towards us -- some of them struggling themselves in the bad weather -- explained why we were going the wrong way in the TSS, and agreed how we would pass. In the end we got through it fine. We got a lee from the Frisian Islands and maneuvered out of the TSS and into sheltered waters, and carried on towards Helgoland, with nice weather and a beautiful sail the next morning.
Great story. Thanks!


I've never used a RAM AIS designation. I only mentioned I would consider it. Oh what a plie on!


I don't like whining to everyone on the radio about my problems, but, I'll put out a Securite instead, should the need ever arise.


I should've worn fireproof clothing. I am appropriately informed, and though that was the USCG advice to me, I won't use RAM. OK. Can we stop the flames now?


I just stopped in to answer a technical question about Class A versus B.


Geesh!
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Old 18-12-2018, 04:47   #86
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Re: "A" versus "B" AIS - worth transmitting?

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3 miles is not enough for a SHIP to see YOU. Maybe in coastal waters, but not in open sea.

Their decision point in open sea is generally about 10 miles. They need to be aware of you well before that in order to set up the crossing with you properly.
Sorry, I want to argue the point. Driving ships has been my work for the last 30 years. Right now my work is 35000t displacement, so a medium sized cargo vessel.

Decision points for manoeuvres, depends a little, normally around 6 miles distance from other ships, more if meeting head on. In confined waters often much less. 10 miles, only when bored.

When meeting sailboats this is a little different. Firstly, sailboats are notoriously unreliable in keeping course, they tack and jibe and follow the wind. This is one of the reasons we do our manoeuvre quite late.

The other reason is much simpler. I need to see the sailboat optically or be able to plot it on Radar to plan my manoeuvre. Optically, the range for navigation lights on sailing yachts is some 2-3 miles. Daytime I can see the yacht about the same distance, unless really looking for it. Radar depends on the sea state, but often sailboats do not show up until some 2-5 miles out.

Then it takes a minute or so to come to a decision. So on average, I would say I change my course about 2 miles off in open waters. Less in confined waters, sometimes much less.

NEVER are collision avoidance decisions made by relying on AIS data. They often show wrong data/vectors. Plotting is ALWAYS done by ARPA, never by AIS, unless I can not get an echo. In this case I give you a very wide berth.

The big advantage about having an AIS on a sailing boat is that you will show up even in rough sea conditions or fog, making it easier to find you.
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Old 18-12-2018, 13:14   #87
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Re: "A" versus "B" AIS - worth transmitting?

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Sorry, I want to argue the point. Driving ships has been my work for the last 30 years. Right now my work is 35000t displacement, so a medium sized cargo vessel.

Decision points for manoeuvres, depends a little, normally around 6 miles distance from other ships, more if meeting head on. In confined waters often much less. 10 miles, only when bored.

When meeting sailboats this is a little different. Firstly, sailboats are notoriously unreliable in keeping course, they tack and jibe and follow the wind. This is one of the reasons we do our manoeuvre quite late.

The other reason is much simpler. I need to see the sailboat optically or be able to plot it on Radar to plan my manoeuvre. Optically, the range for navigation lights on sailing yachts is some 2-3 miles. Daytime I can see the yacht about the same distance, unless really looking for it. Radar depends on the sea state, but often sailboats do not show up until some 2-5 miles out.

Then it takes a minute or so to come to a decision. So on average, I would say I change my course about 2 miles off in open waters. Less in confined waters, sometimes much less.

NEVER are collision avoidance decisions made by relying on AIS data. They often show wrong data/vectors. Plotting is ALWAYS done by ARPA, never by AIS, unless I can not get an echo. In this case I give you a very wide berth.

The big advantage about having an AIS on a sailing boat is that you will show up even in rough sea conditions or fog, making it easier to find you.
How well do the radar reflectors carried on many sailboats show up on your radar? Have you seen any difference in the type of reflector? Any advice on placing them? Is it any easier to track an "AIS only" (no radar reflection) target when it is transmitting true heading and not just COG?

I know that COG varies a lot when sway distorts the COG GPS calculation. A small vessel sways a lot in a seaway with swells. True heading should be much more stable. Is that your experience?
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Old 18-12-2018, 16:21   #88
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Re: "A" versus "B" AIS - worth transmitting?

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How well do the radar reflectors carried on many sailboats show up on your radar? Have you seen any difference in the type of reflector? Any advice on placing them? Is it any easier to track an "AIS only" (no radar reflection) target when it is transmitting true heading and not just COG?

I know that COG varies a lot when sway distorts the COG GPS calculation. A small vessel sways a lot in a seaway with swells. True heading should be much more stable. Is that your experience?
Boats with reflectors show up much better. That is very clear. Conditions bad enough, even those can disappear in the clutter. Modern Radars can make this problem worse, as they use digital declutter. Most yachts today use the cylindrical type of Radar reflector. I can not say if this is better than the round ones. There must be some tests around.

AIS targets show up under all conditions. This is very good, because it makes the yacht very visible.

As for tracking, in heavy conditions, both COG and Heading will be fairly unstable unless you have a good (expensive) heading sensor. But for me these data are not important. Once I know the yacht is there I can look out the window and see what she is actually doing. I guess other officers see this differently, but I am still very much old school.
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Old 18-12-2018, 17:05   #89
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Re: "A" versus "B" AIS - worth transmitting?

MartinR


Thanks very much. And... I like old school.
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Old 18-12-2018, 19:22   #90
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Re: "A" versus "B" AIS - worth transmitting?

Quote:
Originally Posted by Dockhead View Post
We do live on different planets. On my planet no such lubberly request would be made.


Rather:


MV Titan, MV Titan [calling by name because we have AIS, not indeed "Eastbound container ship"], this is SV Dolphin SV Dolphin, over.


SV Dolphin, this is MV Titan


Zero Nine?


Going to Zero Nine.


Titan, Dolphin. Good afternoon, sir. We are the sailing vessel 10 miles off your starboard bow on course 070. We make our CPA with you 5 cables and cannot alter course to port because we are hard on the wind, and tacking would take us into the TSS. Would you be so kind as to alter a few degrees to port so that we can pass behind you? Over.


Dolphin, Titan. I'm altering my course to port. Maintain your course and speed. Over.


Titan, Dolphin. Many thanks. Good watch. Dolphin going back to one six.


Click click.




Note:


1. Nobody ever talks about who is stand on and who is give way (and for God's sake no bloody "right of way"). Nobody cares because we are making special passing arrangements in any case. Don't insult the intelligence of another mariner by lecturing him about the COLREGs.

——I never lectured about no COLREGS, not sure what you are smoking?
The “Right of Way” was from a previous poster who mentioned a radio transmission advising he had his sail up.
(Go back and read the thread again)——






2. Nobody says "to avoid collision". What is that about? What a silly waste of airtime.

————Me neither, just trying to guess what the guy was saying who suggested calling on the VHF to say his chute was up.———-



3. Request made in good time -- 10 miles out.

———Good idea.———


4. Ship identified by name.

——-Wow, great idea.——


5. What you want is formulated as a polite request, and what you want the ship to do is stated succinctly and clearly.

———Thx, great idea again, thx for the lecture.——





I have had dozens of conversations like that, and listened to probably hundreds. The only time anyone ever refused was because of other traffic, and we simply agreed on a different way to deal with the situation.
——-I have never called anybody on VHF to ask them to alter course because I was sailing, but I would if it was really important I guess, or I would tack or fall off, crank up the engine, whatever.——-
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