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Old 14-04-2015, 08:58   #181
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Re: Phuket! I have "Right of Way"

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Originally Posted by Dockhead View Post
What kind of radar do you have?

I have never used recreational MARPA which gave accurate and consistent data. It is of course still very useful, if you don't have AIS, but I don't think you can get an accurate CPA from 10 miles out with recreational MARPA.

It works better in calm conditions, and if you have really good, gyro-stabilized heading data.

The root problem, I suspect, is that recreational radars have too much beam width to give you an accurate enough bearing. Clever processing can average out a wobbly bearing (and maybe Furuno is better than others in this), but when you get right down to it, I suspect you need something with a narrower beam, than a recreational domed radar scanner, for good MARPA. I think you need at least an open array.
The one with MARPA was a Raymarine. That was in 2002 and I believe now they should be way better. Anyway if you could get a fix on the radar you could have MARPA working for several targets. 9/10 miles would not be a problem to use it (detect ships). Never used AIS but I think the information you get regarding relative speed and relative direction to each boat or ship regarding your boat is very similar.

Not saying by any means that AIS is not great. Regarding the MARPA the best advantage (on a dual reception/emission AIS set) is that you are seen clearly by a ship even on a bad sea state situation and that you have the name of the ship in case you want or need to contact him by radio.

Regarding safety, all you can get is not too much if you sail on a high transit zone specially with bad visibility. On the med I almost never turn my radar on (except at night), on the Portuguese coast or Galicia in the summer is madness to navigate without one due to deep fog even during the day (and lots of fishing boats).
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Old 14-04-2015, 09:09   #182
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Re: Phuket! I have "Right of Way"

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Originally Posted by transmitterdan View Post
I am aware that Indonesian commercial vessels run without AIS. That is not the problem we were discussing. We were discussing ships with AIS "ignoring" class B AIS messages.

,,.
There was a discussion on another forum about turning off class B signals and it was there that I learned that on very heavy traffic situations they put class B off (filter). I remember it had to do with too many signals and being confusing and If I am remembering right the ones that stated that were professional ship sailors/captains.

" The problem with AIS Class B targets with regards to filtering is, depending on scenario, you may wish to have a filter that prevents all Class B targets being shown either as sleeping or activated, or you may wish to activate filtered targets under certain special conditions. Class B targets typically apply widely different safety zones compared to interactions between Class A targets, because of their differences in size and manoeuvrability. Particularly in busy areas, small craft often pass closer to ships than is generally considered safe for ship-to-ship encounters, even though needing particular alertness by the small craft skipper.

For this reason, especially in areas that are crowded with small craft but that also have appreciable shipping movements - such as in the Solent area of the UK - it could well be the case that any activation of Class B targets will cause almost constant activation of the Closest Point of Approach (CPA) alarm on the ship - continually distracting the navigating officer/pilot. A 1.0 NM CPA may be appropriate for ship-to-ship encounters in such an area, but many small craft skippers will be quite happy approaching ships at very much closer distances. Therefore, filtering of all AIS Class B targets, together with preventing their activation, may be the appropriate strategy in such areas to avoid possibly dangerous alarm distraction of the bridge team. "


http://www.panbo.com/archives/2010/1...dr_norris.html
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Old 14-04-2015, 09:13   #183
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Re: Phuket! I have "Right of Way"

We occasionally use MARPA on our 2014 Raymarine. By occasionally I mean generally for the occasional vessel without AIS or for squall tracking, but I find AIS much more accurate in most cases. Targets are lost more easily with MARPA but it's still quite usable most of the time.
Polux we have sailed the Galician and Portuguese coasts a couple of times, spending a few months each time between gijon and the algarve. I remember reading that fog was common, something like 50% of the time between June and August. We rarely encountered fog in that period, it seemed like a lot less than even 1 day/week, but when we did the radar was a godsend! Last year we passed close to one of the windmills just off the coast in less then 20m visibility. I'd hate to think what would happen without radar in that case
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Old 14-04-2015, 09:44   #184
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Re: Phuket! I have "Right of Way"

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Originally Posted by nigel1 View Post
Class A AIS should transmit a vessels compass heading (gyro), if the various systems have been integrated correctly. If the gyro has an heading error, then the AIS will transmit the incorrect heading.
AIS should transmit both heading (true) and course over ground (true).
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Old 14-04-2015, 09:50   #185
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Re: Phuket! I have "Right of Way"

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Originally Posted by monte View Post
We occasionally use MARPA on our 2014 Raymarine. By occasionally I mean generally for the occasional vessel without AIS or for squall tracking, but I find AIS much more accurate in most cases. Targets are lost more easily with MARPA but it's still quite usable most of the time.
Polux we have sailed the Galician and Portuguese coasts a couple of times, spending a few months each time between gijon and the algarve. I remember reading that fog was common, something like 50% of the time between June and August. We rarely encountered fog in that period, it seemed like a lot less than even 1 day/week, but when we did the radar was a godsend! Last year we passed close to one of the windmills just off the coast in less then 20m visibility. I'd hate to think what would happen without radar in that case
The problem is that most boats you find out there do not have AIS, meaning most recreational sailboats and mostly most fishingboats even if with considerable size. Great for ships but you need the MARPA for fishingboats that are a lot on those coasts.

The fog is mostly in June (almost all mornings and sometimes all day on some parts of those coasts) and is less on July but very frequent on the first 15 days and occasional in August or September.

More than 35 years ago I sailed out of Cascais to Peniche on a traditional sailboat without engine (perfect time and wind on the first hours of the morning) and got caught on the deepest wet fog you can imagine. The wind almost disappeared and the canvas wet sails did not help. I passed 24 hours without any visibility making tacks between the Cabo da Roca (the Western point of Europe) and the almost continuous line of ships that pass offshore.

The good thing is that the wet fog increases sound transmission so I pointed to shore till I heard the breakers on the cape and turned offshore till I heard the sound of ship engines....What a day!!! I was solo and almost without food....but I had wine
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Old 14-04-2015, 10:28   #186
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Re: Phuket! I have "Right of Way"

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Originally Posted by Dockhead View Post
From the moment that the vessels are in sight of one another, and a risk of collision exists, Vessel A is obligated to hold course and speed, and Vessel B is obligated to maneuver to stay clear, avoiding if possible turning to starboard and avoiding if possible passing close ahead of Vessel A, and avoiding small changes of course or speed which cannot be easily perceived on the other vessel.
I am late to this discussion, and the subject is fairly worn out from all directions, but I want to comment on the portion of one of Dockhead's posts (in bold print above), as it seems contrary to good seamanship and guidance given for action by Vessel B in a crossing situation.

If Vessel B is obliged to stay clear of Vessel A in a crossing situation, Vessel B holds Vessel A to starboard forward of his beam in a leading situation (bows of both vessels on the same side of the line of sight).

If Vessel B evaluates that danger will result from his standing on, he must take action to avoid Vessel A. Danger exists if the vessels are estimated to pass very close to each other (zero or near zero bearing rate).

Vessel B has two options...either maneuver to pass ahead of Vessel A or maneuver to pass astern of Vessel A.

One option is to over lead him (having greater speed across the line of sight than him) by increasing speed, or by turning to port to put him closer to the beam (or both). Vessel A will then draw to the right. Either of these actions will cause Vessel B to pass ahead of Vessel A.

The second option is to slow or turn to starboard toward the line of sight of Vessel A (or both). This ensures that the bearing of Vessel A will draw left, causing Vessel B to pass astern of Vessel A. An aggressive maneuver placing the bow on the opposite side of the line of sight (and Vessel A off Vessel B's port bow) should make intentions clear.

This second option clearly is less risky. Maneuvering to starboard across the line of sight will allow Vessel A to clearly see the effect of the maneuver. The CPA can be controlled, and maximized if desired. Because bearing rates are higher than option one, the duration of the interaction is shortened.

Therefore, turning to starboard is not discouraged but encouraged if risk is to be minimized.

What about an in extremis situation requiring both vessels to maneuver radically in an attempt to avoid collision? Again, Vessel B's best action is to turn to starboard. Such a maneuver anticipates Vessel A's turn to starboard. It also presents the bow, the strongest part of a vessel, to the impact, and protects the propulsion equipment and engine room. The starboard turn toward the "lagging" line of sight (bows on opposite sides of the line of sight), if it can be achieved, will assure clearing the other vessel.
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Old 14-04-2015, 11:22   #187
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Re: Phuket! I have "Right of Way"

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Originally Posted by fryewe View Post
I am late to this discussion, and the subject is fairly worn out from all directions, but I want to comment on the portion of one of Dockhead's posts (in bold print above), as it seems contrary to good seamanship and guidance given for action by Vessel B in a crossing situation.

If Vessel B is obliged to stay clear of Vessel A in a crossing situation, Vessel B holds Vessel A to starboard forward of his beam in a leading situation (bows of both vessels on the same side of the line of sight).

If Vessel B evaluates that danger will result from his standing on, he must take action to avoid Vessel A. Danger exists if the vessels are estimated to pass very close to each other (zero or near zero bearing rate).

Vessel B has two options...either maneuver to pass ahead of Vessel A or maneuver to pass astern of Vessel A.

One option is to over lead him (having greater speed across the line of sight than him) by increasing speed, or by turning to port to put him closer to the beam (or both). Vessel A will then draw to the right. Either of these actions will cause Vessel B to pass ahead of Vessel A.

The second option is to slow or turn to starboard toward the line of sight of Vessel A (or both). This ensures that the bearing of Vessel A will draw left, causing Vessel B to pass astern of Vessel A. An aggressive maneuver placing the bow on the opposite side of the line of sight (and Vessel A off Vessel B's port bow) should make intentions clear.

This second option clearly is less risky. Maneuvering to starboard across the line of sight will allow Vessel A to clearly see the effect of the maneuver. The CPA can be controlled, and maximized if desired. Because bearing rates are higher than option one, the duration of the interaction is shortened.

Therefore, turning to starboard is not discouraged but encouraged if risk is to be minimized.

What about an in extremis situation requiring both vessels to maneuver radically in an attempt to avoid collision? Again, Vessel B's best action is to turn to starboard. Such a maneuver anticipates Vessel A's turn to starboard. It also presents the bow, the strongest part of a vessel, to the impact, and protects the propulsion equipment and engine room. The starboard turn toward the "lagging" line of sight (bows on opposite sides of the line of sight), if it can be achieved, will assure clearing the other vessel.
Thank you for catching that slip! Yes, you are correct, and of course you avoid (where practical) turning to PORT, not starboard! A typo on my part.

This analysis seems all exactly right to me. The first option, involving altering course to pass ahead of the stand-on vessel, is discouraged by Rule 15. It is especially dangerous for a slower vessel to pass ahead of a faster vessel (due to the difficulty of unwinding a problem if you calculate wrong, the other vessels speeds up, etc.), so I guess the second option would be just about universal as between leisure vessels and ships.

My own usual maneuver when keeping clear of a ship on a perpendicular course (typical Channel crossing situation) is to make a large alteration to come onto a reciprocal course at least a mile from the ship's course line. Then turn again and cross his wake a few cables behind. If I'm the stand-on vessel and I am doing this before having stood on for very long, I do (contrary to MCA advice) like to give an apologetic call on the Ch. 13 just to let the other bridge know that I have taken matters into my own hands.

I do not like to pass ahead of ships, and if a ship in a give-way position has maneuvered, but is giving me less than say two miles, then I might well still do this reciprocal course maneuver anyway to pass behind. The ship's bridge could be confused by this -- he has fulfilled his duty, he thinks, and everyone is safe. So I apologize and explain on the radio that I simply prefer to go behind.

Whenever I discuss collision avoidance with commercial mariners, I beg them to not maneuver to pass behind us. The COLREGS discourage (n.b. but do not forbid!) the give-way vessel from maneuvering to pass ahead, but I think this is just wrong in the case of a faster ship and slower yacht. Plus there is just generally less which can go wrong with this kind of crossing -- especially when encountering a leisure sailor who is not skilled in collision avoidance, who might not calculate the crossing well, and just when he is supposed to be passing safely ahead, panics, and suddenly stops or turns around, thinking he is following the Johnny O'Day rule, when in fact he is about to kill himself. This is a nightmare scenario. My advice to commercial mariners is to pass ahead, not behind, of WAFIs, where possible, since you can't depend on us standing on properly, and even those of us who understand our duties, often just do not like to pass ahead of you.
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Old 14-04-2015, 11:33   #188
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Re: Phuket! I have "Right of Way"

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There was a discussion on another forum about turning off class B signals and it was there that I learned that on very heavy traffic situations they put class B off (filter). I remember it had to do with too many signals and being confusing and If I am remembering right the ones that stated that were professional ship sailors/captains.

" The problem with AIS Class B targets with regards to filtering is, depending on scenario, you may wish to have a filter that prevents all Class B targets being shown either as sleeping or activated, or you may wish to activate filtered targets under certain special conditions. Class B targets typically apply widely different safety zones compared to interactions between Class A targets, because of their differences in size and manoeuvrability. Particularly in busy areas, small craft often pass closer to ships than is generally considered safe for ship-to-ship encounters, even though needing particular alertness by the small craft skipper.

For this reason, especially in areas that are crowded with small craft but that also have appreciable shipping movements - such as in the Solent area of the UK - it could well be the case that any activation of Class B targets will cause almost constant activation of the Closest Point of Approach (CPA) alarm on the ship - continually distracting the navigating officer/pilot. A 1.0 NM CPA may be appropriate for ship-to-ship encounters in such an area, but many small craft skippers will be quite happy approaching ships at very much closer distances. Therefore, filtering of all AIS Class B targets, together with preventing their activation, may be the appropriate strategy in such areas to avoid possibly dangerous alarm distraction of the bridge team. "


Panbo: The Marine Electronics Hub: Class B AIS filtering, the word from Dr. Norris
You should install AIS, Polux, by all means! Just about everyone who takes the plunge, says that it's the single best thing they ever installed on their boat. It's really revolutionary.


Talking about "switching off" AIS in busy areas, we should distinguish between alarms, and the display of targets.

Naturally commercial mariners, and not only commercial mariners, switch off the alarms in busy areas. Just like you would switch off your guard zones. None of these tools is worth anything in crowded, close quarters, like the Solent, where vessels are turning and will have momentary collision courses with you by the dozens. You switch them all off, and not just Class B, and use your eyes.

You would never want to switch off the target displays, however, in my opinion. On the Simrad (and probably other) sets, the target symbols turn bold when alarm criteria are reached. This is really useful.

But even that is not the main thing, in crowded harbours and bays. This is all close quarters maneuvering which is a very different problem. You just stay out of the shipping channels, and maneuver proactively with other leisure vessels. You have to keep a sharp visual watch. Guard zones and AIS alarms are of no value at all in that situation.
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Old 14-04-2015, 12:40   #189
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Re: Phuket! I have "Right of Way"

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...

Talking about "switching off" AIS in busy areas, we should distinguish between alarms, and the display of targets.

Naturally commercial mariners, and not only commercial mariners, switch off the alarms in busy areas. Just like you would switch off your guard zones. None of these tools is worth anything in crowded, close quarters, like the Solent, where vessels are turning and will have momentary collision courses with you by the dozens. You switch them all off, and not just Class B, and use your eyes.

You would never want to switch off the target displays, however, in my opinion. On the Simrad (and probably other) sets, the target symbols turn bold when alarm criteria are reached. This is really useful.

....
He is not talking about shutting off the alarm but about shutting off AIS B signals because they make the alarm go on and on.

Yes someday I will have an AIS but it will be only a completely effective toll when all recreational boats and fishing boats would have one on mandatory terms. As it is, with most of the fishing boats and recreational boats not having one, it is only good for ships...and you will need a radar anyway for the others.
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Old 14-04-2015, 12:42   #190
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Re: Phuket! I have "Right of Way"

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My own usual maneuver when keeping clear of a ship on a perpendicular course (typical Channel crossing situation) is to make a large alteration to come onto a reciprocal course at least a mile from the ship's course line. Then turn again and cross his wake a few cables behind. If I'm the stand-on vessel and I am doing this before having stood on for very long, I do (contrary to MCA advice) like to give an apologetic call on the Ch. 13 just to let the other bridge know that I have taken matters into my own hands.

I do not like to pass ahead of ships, and if a ship in a give-way position has maneuvered, but is giving me less than say two miles, then I might well still do this reciprocal course maneuver anyway to pass behind. The ship's bridge could be confused by this -- he has fulfilled his duty, he thinks, and everyone is safe. So I apologize and explain on the radio that I simply prefer to go behind.

Whenever I discuss collision avoidance with commercial mariners, I beg them to not maneuver to pass behind us. The COLREGS discourage (n.b. but do not forbid!) the give-way vessel from maneuvering to pass ahead, but I think this is just wrong in the case of a faster ship and slower yacht. Plus there is just generally less which can go wrong with this kind of crossing -- especially when encountering a leisure sailor who is not skilled in collision avoidance, who might not calculate the crossing well, and just when he is supposed to be passing safely ahead, panics, and suddenly stops or turns around, thinking he is following the Johnny O'Day rule, when in fact he is about to kill himself. This is a nightmare scenario. My advice to commercial mariners is to pass ahead, not behind, of WAFIs, where possible, since you can't depend on us standing on properly, and even those of us who understand our duties, often just do not like to pass ahead of you.
Wow.

So, Dockhead, you're saying that as the stand on vessel, with the give way vessel broad on your port bow, your customary practice is to turn to port (reciprocal to his course) to pass astern of him? That is dangerous and contrary to COLREGS.

I have to say I find that astonishing. If the give way vessel turns to starboard, as the rules encourage and as is common practice when a close encounter is evaluated, you can begin a dance of death. Your maneuver seems intended to shift the situation to a meeting situation, but you are depending on his analysis and reaction timing to reflect your own, which as you know is not necessarily a good assumption.

And you also say that you encourage commercial masters to, in every case, pass ahead when in a crossing situation, because skippers of recreation vessels can't be relied on to stand on. Please don't do that. Such action would make your choice of (improper) action less risky, but at increased risk to those who adhere to the COLREGS.
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Old 14-04-2015, 13:54   #191
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Re: Phuket! I have "Right of Way"

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Wow.

So, Dockhead, you're saying that as the stand on vessel, with the give way vessel broad on your port bow, your customary practice is to turn to port (reciprocal to his course) to pass astern of him? That is dangerous and contrary to COLREGS.

I have to say I find that astonishing. If the give way vessel turns to starboard, as the rules encourage and as is common practice when a close encounter is evaluated, you can begin a dance of death. Your maneuver seems intended to shift the situation to a meeting situation, but you are depending on his analysis and reaction timing to reflect your own, which as you know is not necessarily a good assumption.

And you also say that you encourage commercial masters to, in every case, pass ahead when in a crossing situation, because skippers of recreation vessels can't be relied on to stand on. Please don't do that. Such action would make your choice of (improper) action less risky, but at increased risk to those who adhere to the COLREGS.
I'm grateful for intelligent criticism like this of my technique, which is really useful for testing and improving it.

I think all of the principles explained in your post are generally correct. But I would like to offer a modest defense.

First of all: The points about the "dance of death" and turns to port are really important. I would not do this reciprocal course maneuver with a turn to port, without radio contact. When it is a turn to starboard (he's coming from my starboard side, but I am under sail), I think it's not at all problematic IF the timing is right. In any case, such a maneuver must be done after a decent period of standing on and some certainty that he has completed his maneuvers. It could the really dangerous -- and you are right to point it out -- if EITHER you are too close (less than a couple of miles) OR he is still maneuvering. So the timing is tricky, which I admit is not a point in favor of this maneuver.

HOWEVER, the stand-on vessel most certainly has the right to maneuver if it has a reasonable belief that the maneuvers of the give-way vessel have not been sufficient to create a safe condition. So I will disagree with you, that this is forbidden by the COLREGS -- it is most certainly not, under this circumstance.

Many ships' bridges calculate their maneuvers based on standing orders and without due consideration of the capabilities of the vessels involved -- which is wrong, but it's an understandable failure which comes from routine. In the Channel, the standing orders are usually one mile CPA. To cross behind another vessel of similar speed to yours, another ship which holds course and speed much more reliably than a yacht under sail, is fine at one mile. But it is really not fine for a fast-moving ship to cross one mile behind a much slower vessel, which on top of that is under sail, and so not sailing nearly as steady a course and speed as another ship would be. It is positively dangerous, because if there is a sudden loss of speed on part of the yacht -- which happens all the time under sail -- the CPA can disappear in a matter of seconds, and then this becomes a really dangerous situation -- a dance of death indeed. So such a crossing gives me every right in the world, as the stand-on vessel, to leave off standing-on and make my own maneuver to create a safe crossing. I won't bother citing the specific language of the Rules on this as you obviously know them well.


If there's a turn to port, besides getting the timing of this maneuver right (at least 2-3 miles off, and AFTER the ship has finished all of its maneuvering and is clearly on a steady course), I will make VHF contact to be sure there is no confusion about my intention. If I can't make VHF contact (unfortunately pretty common), then I will heave-to, stop, or turn right around, before I get within 2 or 3 miles of his courseline. I will pretty much never be willing to pass within a mile of the bow of a fast-moving ship -- you could say, that's in my own "standing orders". The COLREGS don't really outline this particular maneuver, but in my opinion it is the only safe policy in dealing with this particular situation, and so in complete compliance with the Rules and with principles of good seamanship.


The inherent problem is slow moving vessels passing ahead of fast ones. Fast vessels are much better able to maneuver to open up the CPA in a crossing than slow ones are (contrary to what many Johnny O'Day-type WAFIs believe), but you can't always be sure that the bridge is aware of what can happen when dealing with a vessel under sail -- how the wind can drop suddenly, etc., etc.. It is much safer when fast vessels pass ahead, if that can be done without creating some other dangerous situation. Or if not, they need to give us at least a couple of miles. And it's really up to us to be proactive about it, and not necessarily accept the solution for a crossing, which has been worked out by the ship's bridge. These solutions, sometimes worked out by rote by a junior officer based on the standing orders, are by no means always safe, and in that case, you have the right, and even the obligation under the Rules to do something yourself.

Besides that, the COLREGS REQUIRE that: "[D]ue regard shall be had to all dangers of navigation and collision and to any special circumstances, including the limitations of the vessels involved,
which may make a departure from these Rules necessary to avoid immediate danger."

The very low speed of small sailing vessels, relative to the speed of ships, and their inability to maintain a very steady course or speed, especially when sailing hard on the wind, is most definitely a "limitation of the vessels involved" which justifies not following the suggestion in Rule 15 about not passing ahead, "if the circumstances of the case admit", which anyway doesn't apply to crossings with sailing vessel.

By the way, the Rule 17(c) suggestion about not turning to port "if the circumstances of the case admit", ALSO does not apply to crossings with sailing vessels, but I agree with you that it is a dangerous and best to avoid. The default turn to starboard is a key part of collision avoidance, in my opinion.

That's my opinion.
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Old 14-04-2015, 15:06   #192
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Re: Phuket! I have "Right of Way"

It's really so dependant on the waters being navigated, obstructions, traffic, weather conditions etc. for instance crossing the English Channel you may be stand on vessel for 2 crossings and give way vessel for 2 others all at the same time and all with less than 30 minute CPAs, so alterations of course may be necessary even though you are standing on. Also in a small harbour we wouldn't expect a commercial ship to alter course and speed for us sailing when the CPA is over 15 minutes and the harbour is full of pleasure yachts. Likewise in congested areas speeds have to be slower and safe passing distances lessened or we wouldn't get anywhere. I too would prefer pass behind ships than less than 1M ahead but I think any alteration of course or speed needs to be done before the give way vessel takes any action to avoid collision.
I don't really understand DH on waiting till the ship has completed manoeuvres to take action, this seems assabout, but maybe I'm reading it incorrectly.
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Old 14-04-2015, 15:56   #193
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Re: Phuket! I have "Right of Way"

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It's really so dependant on the waters being navigated, obstructions, traffic, weather conditions etc. for instance crossing the English Channel you may be stand on vessel for 2 crossings and give way vessel for 2 others all at the same time and all with less than 30 minute CPAs, so alterations of course may be necessary even though you are standing on. Also in a small harbour we wouldn't expect a commercial ship to alter course and speed for us sailing when the CPA is over 15 minutes and the harbour is full of pleasure yachts. Likewise in congested areas speeds have to be slower and safe passing distances lessened or we wouldn't get anywhere. I too would prefer pass behind ships than less than 1M ahead but I think any alteration of course or speed needs to be done before the give way vessel takes any action to avoid collision.
I don't really understand DH on waiting till the ship has completed manoeuvres to take action, this seems assabout, but maybe I'm reading it incorrectly.
Well, you can't know that the give-way vessel's maneuver was ineffective, until after he has made it. So this is a different phase of the crossing.

Everyone is free to maneuver prior to risk of collision arising, and vessels in sight of one another. So if you would be the stand-on vessel in a crossing, but you don't want to get into a crossing situation at all, and you have detected this early (generally more than 10 miles) and can work out a maneuver -- this is fine.

What I am talking about is different. Let's say I will be the stand-on vessel -- I am trying to get through a line of ships in the Channel, say. I see the ship more than 10 miles off, but I'm going to proceed and let him make his move, because I can't really get across this area without some ship altering course.

So I am standing on, and hoping that he alter to let me pass behind him, or at least ahead with plenty of room. I am standing on as I am required, and giving him the chance to make his move. I see him make his move (much easier to discern with AIS or MARPA, than with hand bearing compass, of course), and now the CPA has opened up, but only to 1 mile, and with me passing ahead.

The bridge of the ship think they've done their job, and will now hold their course and speed. But I don't agree that this is a safe crossing configuration.

So now the next phase of COLREGS procedure comes into play:

"Rule 17
Action by stand-on vessel
(a) (i) Where one of two vessels is to keep out of the way the other shall keep her course and speed.
(ii) The latter vessel may however take action to avoid collision by her manoeuvre alone, as soon as it becomes apparent to her that the vessel required to keep out of the way is not taking appropriate action in compliance with these Rules."

So I'm free to maneuver if it is "apparent to me" that the give-way vessels maneuver was not enough to create a safe situation.

One mile ahead of her, when she if making double or triple my speed, is not a safe situation.
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Old 14-04-2015, 16:33   #194
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Re: Phuket! I have "Right of Way"

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Originally Posted by Dockhead View Post
First of all: The points about the "dance of death" and turns to port are really important. I would not do this reciprocal course maneuver with a turn to port, without radio contact. When it is a turn to starboard (he's coming from my starboard side, but I am under sail), I think it's not at all problematic IF the timing is right. In any case, such a maneuver must be done after a decent period of standing on and some certainty that he has completed his maneuvers. It could the really dangerous -- and you are right to point it out -- if EITHER you are too close (less than a couple of miles) OR he is still maneuvering. So the timing is tricky, which I admit is not a point in favor of this maneuver.

I agree with all of this. With an R/T call, which is always smart, and intentions acknowledged and agreed to, safety is improved immensely.

HOWEVER, the stand-on vessel most certainly has the right to maneuver if it has a reasonable belief that the maneuvers of the give-way vessel have not been sufficient to create a safe condition. So I will disagree with you, that this is forbidden by the COLREGS -- it is most certainly not, under this circumstance.

My choice of 'contrary to COLREGS' was poor. 'Discouraged by COLREGS' would have been better. Of course, no prudent action is discouraged if unsafe conditions exist.

Many ships' bridges calculate their maneuvers based on standing orders and without due consideration of the capabilities of the vessels involved -- which is wrong, but it's an understandable failure which comes from routine. In the Channel, the standing orders are usually one mile CPA. To cross behind another vessel of similar speed to yours, another ship which holds course and speed much more reliably than a yacht under sail, is fine at one mile. But it is really not fine for a fast-moving ship to cross one mile behind a much slower vessel, which on top of that is under sail, and so not sailing nearly as steady a course and speed as another ship would be. It is positively dangerous, because if there is a sudden loss of speed on part of the yacht -- which happens all the time under sail -- the CPA can disappear in a matter of seconds, and then this becomes a really dangerous situation -- a dance of death indeed. So such a crossing gives me every right in the world, as the stand-on vessel, to leave off standing-on and make my own maneuver to create a safe crossing. I won't bother citing the specific language of the Rules on this as you obviously know them well.


If there's a turn to port, besides getting the timing of this maneuver right (at least 2-3 miles off, and AFTER the ship has finished all of its maneuvering and is clearly on a steady course), I will make VHF contact to be sure there is no confusion about my intention. If I can't make VHF contact (unfortunately pretty common), then I will heave-to, stop, or turn right around, before I get within 2 or 3 miles of his courseline. I will pretty much never be willing to pass within a mile of the bow of a fast-moving ship -- you could say, that's in my own "standing orders". Mine as well. I will not cross the track of a large vessel without significant sea room. The key is early action, before the give way vessel anticipates the need for action, and for interaction with a single vessel, the solution is simple. The geometry is that of a leading situation...both vessels' bows on the same side of the line of sight. One simply has to minimize his own speed to lower his contribution to the bearing rate. Slowing is my preferred action. Since I am already at low speed, my speed change is likely invisible to the other vessel (I don't have AIS).The COLREGS don't really outline this particular maneuver, but in my opinion it is the only safe policy in dealing with this particular situation, and so in complete compliance with the Rules and with principles of good seamanship.

The inherent problem is slow moving vessels passing ahead of fast ones. Fast vessels are much better able to maneuver to open up the CPA in a crossing than slow ones are (contrary to what many Johnny O'Day-type WAFIs believe), but you can't always be sure that the bridge is aware of what can happen when dealing with a vessel under sail -- how the wind can drop suddenly, etc., etc.. It is much safer when fast vessels pass ahead, if that can be done without creating some other dangerous situation. Or if not, they need to give us at least a couple of miles. And it's really up to us to be proactive about it, and not necessarily accept the solution for a crossing, which has been worked out by the ship's bridge. These solutions, sometimes worked out by rote by a junior officer based on the standing orders, are by no means always safe, and in that case, you have the right, and even the obligation under the Rules to do something yourself.

Besides that, the COLREGS REQUIRE that: "[D]ue regard shall be had to all dangers of navigation and collision and to any special circumstances, including the limitations of the vessels involved,
which may make a departure from these Rules necessary to avoid immediate danger."

The very low speed of small sailing vessels, relative to the speed of ships, and their inability to maintain a very steady course or speed, especially when sailing hard on the wind, is most definitely a "limitation of the vessels involved" which justifies not following the suggestion in Rule 15 about not passing ahead, "if the circumstances of the case admit", which anyway doesn't apply to crossings with sailing vessel.

By the way, the Rule 17(c) suggestion about not turning to port "if the circumstances of the case admit", ALSO does not apply to crossings with sailing vessels, but I agree with you that it is a dangerous and best to avoid. The default turn to starboard is a key part of collision avoidance, in my opinion.

That's my opinion.
I think we are generally in agreement. See my comments in blue above.

One other factor that I don't think has been mentioned here that I take into account is wake effects. A fast moving heavy deep draft vessel passing close aboard develops a dangerous wake for small boats. I have taken some hard knocks falling off wakes. By allowing vessels to pass ahead, i can more easily take on a wake. As a result of slamming hard off a couple, I now maneuver to take the wake on the bow as soon as the vessel is obviously passing clear, if the way is clear. I point the stern of the vessel and look for the wake. When I can see and evaluate it, I turn to take it on the bow.
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Old 14-04-2015, 18:32   #195
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Re: Phuket! I have "Right of Way"

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Originally Posted by charliehows View Post
forgive me if I'm yawning but this long, boring discussion over the miniscule semantic veracities of 'colregs' leaves me a little bemused. I've sailed for 50ish years never having heard of 'colregs' til i read it in this forum, I've got a rough idea you keep the other bloke to your left when approaching; commercial shipping, which is pretty much anything big or ugly, has 'right of way' - let me state that again, 'right of way' - which is not a legal term dating back to the magna bloody carta, it's a nice simple practical way of saying keep out of the other blokes way; and, finally, if in doubt, keep out of the other blokes way, he could be some a#%*hole whos read 3000 pages of colregs and still doesnt know what hes doing but hes damned sure hes got 'right of way' and means to run you down to prove it...
What you say is true. The majority of boaters on the water have not heard of the COLREGS let alone understand them.
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