Phuket! I have "Right of Way"

[44'cruisingcat]

Clearly this guy didn't: "“The dive boat was coming from my right side and I wasn’t sure if he could see me or not… I maintained course and speed, which is what I’m supposed to do under the law."

[monte]

That make a sense DH but I would prefer alter course before the give way vessel alters course. Obviously very situational again, but I count it as a fail on my part if I force a ship to alter course or speed to avoid close quarters with me, unless it's unavoidable. There are plenty of reasons why the stand on vessel may have to alter course or speed as I mentioned above, obstructions, wind, weather, currents, being the give way vessel in another crossing situation etc.
Altering your own course is more likely to be appreciated by a ship before they alter course, so long as it's done well beforehand. Yes AIS helps a lot as you can tell in real time well ahead if the ship has altered course or speed before taking any action. I would think in most situations if the distance between the vessels is over 5M and CPA over 25 minutes it's acceptable for the stand on vessel to alter course and/or speed to increase the CPA without a wtf from the officer on duty . Under those distances/times a radio call would be my choice to discuss. Failing that if the CPA were under a mile with me passing ahead I would also change course and head for the ships stern with at least a 20 degree course change, wind permitting, or slow down.

[american]

Originally Posted by Dockhead

You have no right to engage in a "pissing contest" over who gives way -- which is just about the most jackass-ish, unseamanlike thing you can imagine. No pro (just about) would ever do it -- it's just alien to seamanship and sea-culture -- it's a kind of stupidity which comes from (low) land culture. A real seaman, on the contrary, feels a bit nervous about and doesn't really like standing on. He would rather be in control, and not in the passive role, which is what standing on is. Standing on is like being the girl in a dance -- it's passive (for a moment), not privileged in any way. For a moment, you are dependent on the other seaman to work out the situation. Giving way is the active role, and is actually more like a privilege, than standing on is. You at least have the "privilege" of deciding the best way to unwind the situation, and of maneuvering in a variety of different ways, unlike the stand-on vessel. The give-way vessel is "in the driver's seat", so to speak, in that phase of a crossing.

This has been IMHO this most relevant and useful bit of the back-and-forth as it applies to this story of the dive boat hitting the sailboat. It's also extremely relevant to operating a vessel in Thai waters. I know it may be wrong (according to regulations) to abandon my Stand On position, but I do not see it as a privilege in Thai waters. It's an impediment, and leaves me in a passive state where the Thai skipper gets to decide what happens next.

To avoid that, I make corrections to pass behind all power boat traffic in these waters, and do it in such a way as to completely remove the potential for conflict and decision making on the part of the other vessel.

Why do I go to this extreme? I'll admit it's because I am an American and was raised with an entitled sense of "right" when it comes to driving or operating a vehicle. Living (and driving) in China for a few years beat this belief out of my head. First on bikes and scooters, then in cars, then when flying (paragliding), and then on the water (sailing). In all cases the safest thing to do is assume the other person not only doesn't know the rules, but if he/she does, those rules will still be ignored. Until I accepted this new "right," I was always pissed off.

I'm better now that I don't have expectations of "right" and actively avoid testing whether or not the other guy does.

A Thai friend once told me they drive the way they do because they believe everything is controlled by fate. There's no personal decision one can make to avoid whatever's already fated to happen, therefore it's hands off the wheel and foot on the accelerator everywhere you go!

[Dockhead]

Originally Posted by monte

That make a sense DH but I would prefer alter course before the give way vessel alters course. Obviously very situational again, but I count it as a fail on my part if I force a ship to alter course or speed to avoid close quarters with me, unless it's unavoidable. There are plenty of reasons why the stand on vessel may have to alter course or speed as I mentioned above, obstructions, wind, weather, currents, being the give way vessel in another crossing situation etc.
Altering your own course is more likely to be appreciated by a ship before they alter course, so long as it's done well beforehand. Yes AIS helps a lot as you can tell in real time well ahead if the ship has altered course or speed before taking any action. I would think in most situations if the distance between the vessels is over 5M and CPA over 25 minutes it's acceptable for the stand on vessel to alter course and/or speed to increase the CPA without a wtf from the officer on duty . Under those distances/times a radio call would be my choice to discuss. Failing that if the CPA were under a mile with me passing ahead I would also change course and head for the ships stern with at least a 20 degree course change, wind permitting, or slow down.

I certainly agree that an early course alteration, prior to risk of collision arising (10+ miles in open water I would say, or 30 mins+ TCPA), should always be Plan "A" in a crossing with a ship, and I absolutely agree that wherever possible you should try to avoid making a ship alter course to avoid you. That's good seamanship -- to stay out of any anti-collision maneuvering in the first place. Obviously much safer and much less of an imposition on the other guys.

But there are a few reasons why you may not be able to do this, however, in every case. First of all, you have to be able to detect and calculate CPA far enough out - -with AIS no problem, but without, very hard. Most ships' bridges, at least around here, will make their move around 10 miles out, and never less than 5 miles or so unless forced to by circumstances. So to make this "early move" it has to be really early indeed. There is a sharp clash of mentality here between recreational sailors and professional mariners, who have completely different horizons of awareness and maneuvering. And this thing is really dangerous.

So if you don't manage for whatever reason to be able to set up the crossing early to avoid any maneuvering, you may already be in the situation where his maneuver is completed, and you are still 5 to 10 miles apart, and you are already supposed to be standing on. You are supposed to be standing on in order not to invalidate his solution of the crossing.


But the biggest obstacle to early solution of crossings is when there are multiple ships around. When you're crossing busy traffic lanes (NOT TSS -- those are different rules and techniques), the ships may be lined up a couple miles apart, and what's worse, may not be in a line at all, more like an armada, seemingly sailing for no other purpose than to run you down . Here you may have to aim to pass right astern of one ship, in order to have a decent interval (maybe only two miles) from the bow of the next one. In some places, like the English Channel, it really can feel like being a squirrel running across a busy autobahn. Sometimes there really isn't any way across that doesn't require some alteration by other traffic.



I digress a little, but this is a common situation -- vessels 3 miles apart, ship has long since maneuvered and set up a CPA of 1 mile, sailboat skipper only just now notices that the ship even exists, and without AIS, he can't perceive that there is a one mile CPA, but thinks he's on a collision course and that the ship has not seen him or has failed to maneuver. He would have passed safely ahead (barely, but safely) if he had only held course and speed, but he can't perceive that. So at TCPA 5 minutes, he slams on the brakes and stops, or turns around, immediately creating a real collision course. The ship's bridge is not paying that much attention as they figure they have long since solved the problem, and are already thinking about the next crossing. The rest you can imagine . . .

[Dockhead]

Originally Posted by american

This has been IMHO this most relevant and useful bit of the back-and-forth as it applies to this story of the dive boat hitting the sailboat. It's also extremely relevant to operating a vessel in Thai waters. I know it may be wrong (according to regulations) to abandon my Stand On position, but I do not see it as a privilege in Thai waters. It's an impediment, and leaves me in a passive state where the Thai skipper gets to decide what happens next.

To avoid that, I make corrections to pass behind all power boat traffic in these waters, and do it in such a way as to completely remove the potential for conflict and decision making on the part of the other vessel.

I think that's exactly the right way to behave in that situation. When you're dealing with that kind of traffic in that kind of place, you can reasonably doubt that anyone is going to follow the Rules, and so your first priority should be avoiding any situation where you are dependent on the maneuvers of an inherently unreliable other boat -- depending on the Thai skipper of a small power boat, for example.

And for purely geometrical reasons, slow boats passing behind faster ones is far safer, than the other way around.

I'm not advocating throwing the Rules out the window -- I'm advocating (a) aggressively taking earliest possible action to avoid risk of collision ever arising with these kinds of boats; and (b) never stand on for more than the absolute minimum time required, if you do get into a risk of collision situation. There may be cases where you don't attempt to stand on at all; that falls under Rule 2(b). In my opinion, the culture of navigation in a particular place may be considered a "limitation of the vessels involved".

In any case, the Rules do not require you, and indeed do not allow you to stand on into danger. If you have a reasonable belief that standing on will only make the situation worse, then don't do it. Never, ever, ever stand on if there is no reasonable expectation that the other vessel will give way.

[Polux]

Originally Posted by monte

That make a sense DH but I would prefer alter course before the give way vessel alters course. Obviously very situational again, but I count it as a fail on my part if I force a ship to alter course or speed to avoid close quarters with me, unless it's unavoidable. There are plenty of reasons why the stand on vessel may have to alter course or speed as I mentioned above, obstructions, wind, weather, currents, being the give way vessel in another crossing situation etc.
Altering your own course is more likely to be appreciated by a ship before they alter course, so long as it's done well beforehand. Yes AIS helps a lot as you can tell in real time well ahead if the ship has altered course or speed before taking any action. I would think in most situations if the distance between the vessels is over 5M and CPA over 25 minutes it's acceptable for the stand on vessel to alter course and/or speed to increase the CPA without a wtf from the officer on duty . Under those distances/times a radio call would be my choice to discuss. Failing that if the CPA were under a mile with me passing ahead I would also change course and head for the ships stern with at least a 20 degree course change, wind permitting, or slow down.

The problem here if you are the stand on vessel is to make very clear to the ship that you have altered your course otherwise you can create a dangerous situation since by the rules on the ship they would expect you to maintain course and speed. Regarding the last paragraph if you head to a ship stern at a distance of 5nm you are going to pass many miles on his stern unless you are permanently changing course to have your boat pointed at his stern. Not very efficient specially if you are sailing.

Regarding what you and dockhead are saying regarding a safe crossing with a ship what I normally do if I am the stand on vessel is to stand on and to see what is the ship option and then I change my own course slightly on the opposed direction the ship is deviating creating a bigger and safer distance on the CPA. If even so I am not satisfied with the CPA distance I just make a big change on my course and pass at is stern.

If I don't understand what the ship is doing or I have doubts I contact them by radio.

I don't think a small alteration of course to give way is any problem on a ship and they are used to do that all the time. The only situation were being me the stand on vessel I will alter radically course first making them see that I am giving way is when I cross with sailingboats that are racing.

[Dockhead]

Originally Posted by Polux

. . . . Regarding the last paragraph if you head to a ship stern at a distance of 5nm you are going to pass many miles on his stern unless you are permanently changing course to have your boat pointed at his stern. Not very efficient specially if you are sailing. . . .

That's actually a classical anti-collision maneuver going back probably centuries.

I agree with Polux that it's not very efficient, but it is totally simple to do, totally simple to remember, excludes any kind of confusion, and guarantees safety. That Monte knows about it speaks highly of his knowledge of seamanship ; in this electronic age I don't think it's taught anymore.

In my opinion, everyone should know this move -- you don't need any electronics at all, or even a HBC to do it successfully.

The only caveat is that you should be sure that the ship understands what you're doing. You shouldn't abruptly go over to this maneuver when you're supposed to be standing on.

[monte]

Your right about that Polux and I probably shouldn't have added that as it's more of an emergency out than proper planning. The usual action to pass astern would be an obvious course change to pass 1M astern. Which leads to an interesting point. 1M CPA is not 1M behind. The CPA is the closest point of approach so if the ship is travelling at 3x our speed, it's likely to be 1M directly ahead at CPA and we would cross it's wake 10 minutes later 3M astern ( in a 90 degree crossing situation)
The same goes for passing ahead. If we pass 3M ahead on his course the CPA will be 10 minutes later when he is close to 1M astern.
Sorry for the thread drift on this! One more point with AIS though, is it's very easy to mistakenly identify an AIS target on the plotter, with a vessel you are looking at with your eyes. You always need to cross check to confirm the vessel you are seeing is the AIS target you assume it is. We do this with distance estimation, vessels heading estimation, hand bearing compass and occasionally radar. More than once we have come across ships not transmitting AIS and mistaken them for another unseen ship transmitting AIS.

[Dockhead]

Originally Posted by monte

. . . One more point with AIS though, is it's very easy to mistakenly identify an AIS target on the plotter, with a vessel you are looking at with your eyes. You always need to cross check to confirm the vessel you are seeing is the AIS target you assume it is. We do this with distance estimation, vessels heading estimation, hand bearing compass and occasionally radar. More than once we have come across ships not transmitting AIS and mistaken them for another unseen ship transmitting AIS.

Very important point!!!

AIS, like chart plotters, is such a powerful tool, that it is easy to be lulled into the sense that it is infallible. Unfortunately, it is not, and confusing a ship broadcasting AIS and with a safe CPA with a ship not broadcasting AIS and on a collision course is the stuff of nightmares.

The way we do this is to always use radar overlay on the plotter. You'll see the red blotch of a radar target overlaid on all the AIS target carets. If you see a red blotch with no AIS target, you know you've got a problem. Then you do a MARPA track on it.

And always a hand bearing compass in the cockpit, and always traditional watchkeeping -- on the alert with eyes and HBC for a constant bearing. Not just relying on AIS alarms.

I find that it is extremely hard to judge even a ship's heading, and forget about its COG, by its aspect, so I don't even try to figure this out with bare eyes. The bearing is the thing.

[Polux]

Originally Posted by Dockhead

That's actually a classical anti-collision maneuver going back probably centuries.

I agree with Polux that it's not very efficient, but it is totally simple to do, totally simple to remember, excludes any kind of confusion, and guarantees safety. That Monte knows about it speaks highly of his knowledge of seamanship ; in this electronic age I don't think it's taught anymore.

In my opinion, everyone should know this move -- you don't need any electronics at all, or even a HBC to do it successfully.

The only caveat is that you should be sure that the ship understands what you're doing. You shouldn't abruptly go over to this maneuver when you're supposed to be standing on.

I have no doubt Monte is an experienced sailor and knows what is doing but sometime all of us say things that are not actually exactly what we want to say.

Assuming a distance of 5NM, perpendicular courses, considering a ship speed of 18K and a sailboat speed of 6k, if you point to the stern of an incoming ship that was previously on a collision course and maintain that course/speed (that is what one should do when changing course to avoid a possible collision) he would pass at about 4NM on the stern of the ship. That is way too much and a not necessary big loss of time and distance. The change of course would be of about 55º.

When on a collision course if we want to give way to the ship what is normal is to change our course in 25º/30º towards the ship. That would clearly indicate to the ship that we have changed course and are giving him way.

Even if the ship had already altered course to avoid a collision, this change of course will be much bigger then the one on the ship and will not create the danger of a collision on another CPA (on the case the ship deviated towards the sailing boat). Anyway provably the Ship would return to the previous course but we should never assume.

With this new course the sailing boat will be pointing initially way ahead of the ship and would pass about one and a half, one mile behind his stern. Off course the sailing boat can always open the course to pass more astern if needed.

Pointing to the ship at 5NM will implicate a change of course of about 55º and with the continuous course alteration needed the sailingboat would be making about a 1/4 of a circle. It is not only the distance lost but the continuous sail trim that would implicate.

I think I had understood what Monte was saying (and in fact I do it even if in fact I do not point to the stern, except on the last phase) but that is a maneuver that one do but not at a distance of 5NM (as he mentioned) but at a much shorter distance.

[markpierce]

Originally Posted by Dockhead

...
But the biggest obstacle to early solution of crossings is when there are multiple ships around. When you're crossing busy traffic lanes (NOT TSS -- those are different rules and techniques), the ships may be lined up a couple miles apart, and what's worse, may not be in a line at all, more like an armada, seemingly sailing for no other purpose than to run you down . Here you may have to aim to pass right astern of one ship, in order to have a decent interval (maybe only two miles) from the bow of the next one. . . .

[Polux]

Originally Posted by monte

... One more point with AIS though, is it's very easy to mistakenly identify an AIS target on the plotter, with a vessel you are looking at with your eyes. You always need to cross check to confirm the vessel you are seeing is the AIS target you assume it is. We do this with distance estimation, vessels heading estimation, hand bearing compass and occasionally radar. More than once we have come across ships not transmitting AIS and mistaken them for another unseen ship transmitting AIS.

I think that is why some Ship Captains prefer to filter AIS B signals on high traffic zones. That can induce a false sense of security since in what regards B signals the boats that have them are still a minority. The eyes and the radar are still the main tolls for a pilot to avoid collisions. AIS is a great help but does not substitute radar that effectively show all the boats around.

Well, regarding main tools I guess that as important as the eyes and the Radar is knowledge and experience and we can assume that a ship's captain has a lot more then the regular yacht skipper.

[fryewe]

Originally Posted by Dockhead

I find that it is extremely hard to judge even a ship's heading, and forget about its COG, by its aspect, so I don't even try to figure this out with bare eyes. The bearing is the thing.

With a known bearing, determining COG by observation is quite easy with practice evaluating the aspect (angle on the bow; ie, the angle between the vessel's bow and the bearing). With AIS, the actual values can be referred to in order to grade your proficiency.

COG of an observed vessel is determined simply by taking a bearing, then determining the reciprocal of that bearing, and adding or subtracting the angle on the bow (depending on whether you see the vessel's port or starboard bow...or quarter).

For example, if a vessel bears 340 and you estimate a 20 degree starboard angle on the bow, his course is estimated by determining the reciprocal of the compass bearing of 340 by subtracting or adding 180 degrees...which is 140 degrees...then swinging that bearing right 20 degrees due to his aspect (in effect subtracting 20 degrees)...making his estimated course 120. (Magnetic...if using a hand bearing compass).

Another great use of estimates of aspect is estimating the speed of a vessel across the line of sight, which is key to knowing whether he will pass ahead or behind on the current course. This requires use of estimates of the sine of the angle on the bow, but for angles up to 40 degrees (which are those of greatest interest for this scenario...high speed vessels with broad aspects will always pass ahead) the sine estimate is simply the angle divided by 60.

If you have an estimate of vessel speed, eg, it's a ferry known to transit at a certain speed, you can instantly evaluate the crossing situation.

For the example used above with a vessel at 340 with a starboard 20 defree angle on the bow, if he is a ferry known to transit at 16 knots, his speed across the line of sight is estimated to be 20/60 x 16 or 5.3 knots. If he is broad on your port beam and you're doing 5 knots, you will have a close interaction, and you can know this with no electronics required. If his angle is starboard 30, his speed across the line of sight is 8 and you're not at risk.

[nigel1]

Originally Posted by Polux

Well, regarding main tools I guess that as important as the eyes and the Radar is knowledge and experience and we can assume that a ship's captain has a lot more then the regular yacht skipper.

Rule 7 has something to say about making assumptions

[Polux]

Originally Posted by downunder

What you say is true. The majority of boaters on the water have not heard of the COLREGS let alone understand them.

Are you not an apologist of the no need of any licence for Captains of recreational boats? (sorry if I am mistaken). If so how can you have the opinion that most boaters don't know the "COLREGS let alone understand them" and oppose a mandatory licence that implicates an examination that assures that to pass it one has to knows COLREGS?