Over-Reliance on AIS -- Collision off Dungeness

[Robin3]

Originally Posted by Polux

It may seem strange to you that seem to rely on electronics to avoid collision but on 95% of the cases you don't need any bearing compass to take a meaningful bearing on this case.

The bearing in degrees is irrelevant what is relevant is if the bearing is constant or not. If it is (approximately) constant then you may be on a collision course, if the boat moves ahead regarding the bearing it is going to pass ahead, if it moves backward than it is going to pass on your stern.

You just need not to move your head, take as reference some fixed part of the boat maintain a steady course and take bearings some minutes apart regarding the position of the ship and that fixed part of boat that serves you as marker.

Only if I had doubts (very few occasions) I use my binoculars and the compass inside for a more precise bearing.

ALL agreed and very relevant, make a stanchion or a sheet winch your friend as a reference point! The caveat is that this does not work at great rangesor unless the visibilty is good, horizon range haze leads to difficulties and the eyeball method cannot be used at the 15 miles proffered by someone earlier. Ship's aspect is very difficult to judge and some ships profiles make them look like they are proceeding stern first on occasion. The important bit is if the constant bearing or not. I often preferred night crossings because the navigation lights gave a clearer idea of a ship's aspect than would a hazy outline in daylight.

When we had radar but no MARPA we also used plotting sheets as well as the electronic bearing/range markers to plot CPAs but in reality these were only used if the target(s) looked like being a problem. Plotting sheets work with eyeball and HBC too for the energetic and it is good practice for future foggy encounters. MY wife became very adept when taking her UK Offshore Yachtmaster quals and I had her on navigator's duty for practical experience.

I would also add especially for those of a nervous disposition that we made a great many Channel crossings without having to make course alterations at all. The gaps in the parade are there, even though it looks like a mouse could not sneak between them on Marine Traffic etc.

[Muckle Flugga]

Originally Posted by Exile

...

One sort of pedantic question: How would a commercial ship under these scenarios know that a sailing vessel is in fact under sail and therefore the stand on vessel? I almost always have some sail up, even when I'm only motoring, and of course I also motor-sail at times too. But any sort of engine propulsion renders us motor vessels, and therefore not subject to stand on status with the larger ship. This can be exacerbated at night, unless perhaps using your tricolor signals that you are under sail alone. Perhaps Class A AIS allows you to transmit this status, but not Class B I don't think (I have a receiver only). If in doubt, I suppose common sense & caution would prevail and a properly run merchant ship would just assume you are under sail. The relatively few times I've resorted to using the radio, I always make a point of identifying myself to the merchant ship as a sailing vessel under sail.

Joking aside, Carsten is right of course. One should show a motorsailing cone in the day, but MOST CERTAINLY a steaming light at night. There are plenty of WAFIS out there who actually pretty much never sail, and motor along with a mainsail up thinking themselves sailors. I would have to assume, as Nigel suggests, that OOWs would regard them as vessels under sail, regardless. Whatever they may also think of them…

[Polux]

Originally Posted by MarkJ

the stand on vessel has the ability to take evasive action till quite late.

I certainly do make plans in case the ships crew are asleep on the bridge... but not till quite close and after I have tried to contact via VHF ...

This is where you, as stand on vessel, can be chased around the ocean by a ship.

Most ships have a company rule of 1 nm cpa, so if you try to increase that to 2 miles they can just come back on their previous course closer to you. You end diverting miles to go past the stern of a vessel that was conning no where near you anyway. That's just ding-a-ling stuff that you wouldn't actually do.

As the stand on vessel its really important to do what Colregs say.

COLREGS regards collision avoidance and the measures that should be taken on that case, I mean the possibility of a collision. There are a distance at what, on the coastal heavy traffic waters of the med, makes no sense to talk about risk of collision (regarding a small sail boat) and I would say that is about 6NM. AT that distance, on most of the cases we are talking of about 20 minutes of sailing time.

At that distance COLREGS do not apply since according to your map and what Nigel says on coastal heavy traffic zones ships take evasive action (apply the COLREGS) at 2 or 3nm of CPA.

So If I preemptively take a small deviation at over 6nm of distance to avoid any risk of collision and therefore the appliance of the COLREGS. I am just making it safer and assuming full control of the situation.

On the very rare eventuality that on coastal waters at 6NM a ship had already assume a collision possibility, have considered me the stand on vessel and make a deviation, I will just adjust mine. If he returns to his course, good for him, it was what I wanted in the first place and I will adjust it again. Everything is done at more than 5nm of CPA. Completely safe and with plenty of time

The only difference regarding this and what you do, when a ship fails to notice you or will pass too close for what you consider comfortable, is that you will be changing your status of stand on vessel at a close distance of a ship, let's say a mile or less while on that ship they may just have noticed you and are changing course in a contradictory way with what you have done.

That is not happening 5nm away but less than 1nm away and can be potentially very dangerous with few minutes before contact.

As I have repetitively told I have been learned to act this way, as the safest option, through formal nautical education with teachers that were ship Captains. I have been told that on a small boat versus a ship the safest way is to avoid a situation that could be considered a possible collision course, where COLREGS will apply.

Not always it is possible due to Islands or other obstructions.

Some have been trying to say here that I don't know what I am doing even if I act according what have been learned with very experienced sea Captains and have my own experience that is very considerable on these situations.

Saying that this way of avoiding any close approach, or possibility of collision course with ships is wrong or contrary of COLREGS or even worse that I did not have an accident because I am lucky does not make any sense.

I do respect the opinion of those that prefer on a 6T boat to act no differently as if they were at the wheel of a 60000T ship, even if I do not feel safe having the possibility of making avoidance maneuvers at less that 1nm of an incoming ship that had not noticed me.

The fact is that it is much more difficult to notice a 6T boat, specially a fiberglass one without AIS, than a 60 000T ship.

[Dockhead]

Originally Posted by Polux

It may seem strange to you that seem to rely on electronics to avoid collision but on 95% of the cases you don't need any bearing compass to take a meaningful bearing on this case.

The bearing in degrees is irrelevant what is relevant is if the bearing is constant or not. If it is (approximately) constant then you may be on a collision course, if the boat moves ahead regarding the bearing it is going to pass ahead, if it moves backward than it is going to pass on your stern.

You just need not to move your head, take as reference some fixed part of the boat maintain a steady course and take bearings some minutes apart regarding the position of the ship and that fixed part of boat that serves you as marker.

Only if I had doubts (very few occasions) I use my binoculars and the compass inside for a more precise bearing.

The hand bearing compass, and even more, a good compass binocular, is a fundamental tool which I think far too few sailors use.


It is true that you can -- and all good sailors do -- recognize ships you don't need to worry about, because a changing bearing is evident to the naked eye, comparing the ship in view with a stanchion. This is really useful because it allows you to concentrate on a few targets and not be distracted by ships which are not a problem.

The problem, however, is that although an obviously changing bearing detectable by the naked eye against a stanchion is proof that you don't have a problem, an apparently unchanging bearing using that method is no proof that you do have a problem, and cannot be the basis for precipitously taking action. You have to dig deeper.

A skillfully used HBC, or better, compass binocs, is adequate, as long as you don't have more targets than you can process at once using this fairly laborious method.

I used this method for decades, and crossed the Channel a few dozen times, using this method, before I had AIS. I kept a notebook and pencil in the cockpit for keeping track of the bearings. It works ok but starts to break down if you have to deal with 3 or more ships at the same time -- a common situation in the Channel. The other disadvantage of it is that although you can determine a slightly changing bearing, it is hard to distinguish a safe 1 mile CPA from a not safe 1 or 2 cables CPA.


Even with plenty of electronics on board now, I still keep compass binocs and HBC in the cockpit, and I certainly start off any analysis of crossing with what my eyes can see -- provided, of course, that there is good visibility.

But the limitation of what you can figure out with your eyes is vividly shown in MarkJ's post above -- something quite a lot of sailors just don't understand.

[Muckle Flugga]

Originally Posted by Dockhead

The hand bearing compass, and even more, a good compass binocular, is a fundamental tool which I think far too few sailors use.


It is true that you can -- and all good sailors do -- recognize ships you don't need to worry about, because a changing bearing is evident to the naked eye, comparing the ship in view with a stanchion. This is really useful because it allows you to concentrate on a few targets and not be distracted by ships which are not a problem.

The problem, however, is that although an obviously changing bearing detectable by the naked eye against a stanchion is proof that you don't have a problem, an apparently unchanging bearing using that method is no proof that you do have a problem, and cannot be the basis for precipitously taking action. You have to dig deeper.

A skillfully used HBC, or better, compass binocs, is adequate, as long as you don't have more targets than you can process at once using this fairly laborious method.

I used this method for decades, and crossed the Channel a few dozen times, using this method, before I had AIS. I kept a notebook and pencil in the cockpit for keeping track of the bearings. It works ok but starts to break down if you have to deal with 3 or more ships at the same time -- a common situation in the Channel. The other disadvantage of it is that although you can determine a slightly changing bearing, it is hard to distinguish a safe 1 mile CPA from a not safe 1 or 2 cables CPA.


Even with plenty of electronics on board now, I still keep compass binocs and HBC in the cockpit, and I certainly start off any analysis of crossing with what my eyes can see -- provided, of course, that there is good visibility.

100% Agree. I keep both handy and use compass binos for bearings frequently on any busyish passage.

[Exile]

Originally Posted by Muckle Flugga

Joking aside, Carsten is right of course. One should show a motorsailing cone in the day, but MOST CERTAINLY a steaming light at night. There are plenty of WAFIS out there who actually pretty much never sail, and motor along with a mainsail up thinking themselves sailors. I would have to assume, as Nigel suggests, that OOWs would regard them as vessels under sail, regardless. Whatever they may also think of them…

Forgot to mention the steaming light at night when motoring, as opposed to just running side lights & stern light under sail, or the tricolor when offshore under sail. But I NEVER forget to use the steaming light when motoring at night. But I DO forget to hoist the inverted cone during daytime motoring, even though I have one onboard! If it's any consolation, I've started hoisting a black ball during daytime anchoring. Hopefully a score of 75% or so is enough to pass the exam.

Also helpful hearing about these issues from the perspective of a commercial ship captain. Thanks Nigel.

[TeddyDiver]

Originally Posted by Polux

On the very rare eventuality that on coastal waters at 6NM a ship had already assume a collision possibility, have considered me the stand on vessel and make a deviation, I will just adjust mine. If he returns to his course, good for him, it was what I wanted in the first place and I will adjust it again. Everything is done at more than 5nm of CPA. Completely safe and with plenty of time.

This is when things start to go south and suddenly there's no more time..

BR Teddy

[Simonsays]

Originally Posted by TeddyDiver

This is when things start to go south and suddenly there's no more time..

BR Teddy

actualy with a CPA > 5nm he is only chasing his own tail.

[Exile]

Originally Posted by Polux:

On the very rare eventuality that on coastal waters at 6NM a ship had already assume a collision possibility, have considered me the stand on vessel and make a deviation, I will just adjust mine. If he returns to his course, good for him, it was what I wanted in the first place and I will adjust it again. Everything is done at more than 5nm of CPA. Completely safe and with plenty of time.

Originally Posted by TeddyDiver

This is when things start to go south and suddenly there's no more time..

BR Teddy

I didn't understand this one either, nor the last bit about sailboats taking different actions based on their small size and lower visibility. Although the Colregs were primarily developed around commercial shipping, they make no distinction b'twn small vs. large, or commercial vs. recreational on these sorts of issues. This appears to be deliberate to promote predictability amongst all vessels out on the water. Having different sets of rules for different types of boats would only add variables & thus confusion it seems.

[jackdale]

Originally Posted by Exile

Having different sets of rules for different types of boats would only add variables & thus confusion it seems.

Size matters (although not in collision avoidance). Maneuverability matters. That should be about all that matters.

[Robin3]

Originally Posted by Exile

Originally Posted by Polux:

On the very rare eventuality that on coastal waters at 6NM a ship had already assume a collision possibility, have considered me the stand on vessel and make a deviation, I will just adjust mine. If he returns to his course, good for him, it was what I wanted in the first place and I will adjust it again. Everything is done at more than 5nm of CPA. Completely safe and with plenty of time.



I didn't understand this one either, nor the last bit about sailboats taking different actions based on their small size and lower visibility. Although the Colregs were primarily developed around commercial shipping, they make no distinction b'twn small vs. large, or commercial vs. recreational on these sorts of issues. This appears to be deliberate to promote predictability amongst all vessels out on the water. Having different sets of rules for different types of boats would only add variables & thus confusion it seems.

Spot on

[Exile]

Originally Posted by jackdale

Size matters (although not in collision avoidance). Maneuverability matters. That should be about all that matters.

[Dockhead]

Originally Posted by Polux

. . .

The only difference regarding this and what you do, when a ship fails to notice you or will pass too close for what you consider comfortable, is that you will be changing your status of stand on vessel at a close distance of a ship, let's say a mile or less while on that ship they may just have noticed you and are changing course in a contradictory way with what you have done.

That is not happening 5nm away but less than 1nm away and can be potentially very dangerous with few minutes before contact. . . . .

1 mile away is close quarters and an emergency situation, in open water. You should not ever find yourself that close unless you are definitely passing astern of the ship. In open water, closer than 3 or 4 miles, IF you are REALLY on a collision course -- and you must be able to determine this with some precision -- you are already entirely free of stand on obligations, but you need to know which way to turn. Usually to starboard, but you have to understand the geometry of the crossing, and you need accurate information about the CPA, and how to make it bigger. If you're using a HBC, you can recognize this from a bearing which is changing more slowly than you need, and you turn in the direction needed to make the bearing change faster. Just be absolutely sure that he is not turning himself. If in doing this you make a turn to port, and he is turning at the same time, this can cause a collision faster than you can understand it is happening.


In crowded areas directly near the coast, as is so often the case in the Med, collision avoidance is actually much simpler. Also in harbors and approaches to harbors. In such places, you know where ships will go -- there are fairways or channels at least contour lines, beyond which you know they won't go. Here you just stay away from where ships will be, until there's no traffic -- simple.

[Dockhead]

Originally Posted by Robin3

ALL agreed and very relevant, make a stanchion or a sheet winch your friend as a reference point! The caveat is that this does not work at great rangesor unless the visibilty is good, horizon range haze leads to difficulties and the eyeball method cannot be used at the 15 miles proffered by someone earlier. Ship's aspect is very difficult to judge and some ships profiles make them look like they are proceeding stern first on occasion. The important bit is if the constant bearing or not. I often preferred night crossings because the navigation lights gave a clearer idea of a ship's aspect than would a hazy outline in daylight.

When we had radar but no MARPA we also used plotting sheets as well as the electronic bearing/range markers to plot CPAs but in reality these were only used if the target(s) looked like being a problem. Plotting sheets work with eyeball and HBC too for the energetic and it is good practice for future foggy encounters. MY wife became very adept when taking her UK Offshore Yachtmaster quals and I had her on navigator's duty for practical experience.

I would also add especially for those of a nervous disposition that we made a great many Channel crossings without having to make course alterations at all. The gaps in the parade are there, even though it looks like a mouse could not sneak between them on Marine Traffic etc.

A little Small World Story -- some six or seven years ago, when I was getting ready to make my very first Channel crossing, Robin helped with a ton of advice, and even calculated a CTS for me using his Neptune program. We knew each other from a different forum.


Concerning radar -- I have never had MARPA that worked very well, and indeed small boat radar is pretty poor for accuracy of bearings (very good for accuracy of range). However, one lovely low-tech radar technique is to set the EBL on the ship in question and just watch how the blip moves in relation to the EBL. The blip will be jigging around due to inaccuracy of the radar, but you can discern the TREND pretty easily. If it is drifting away from EBL, you are ok. If it is just walking down the EBL -- you've got a problem. You don't need to do a plot or anything -- very simple and useful trick.

[boatman61]

Originally Posted by MarkJ

Here is a great example why you eye is bloody useless by itself, or even 2 of them.
Just being sitting in the cockpit with a tall ship captain looking at 3 boats, anchored, and asking which of the 3 is closest and which is further away.

OK, its more difficult to do it by photo, but...

Hull colour, like light brightness can make distance perception inaccurate.

Here, 2 grey boats look further away than the white.
Size also makes the larger one look closer.

So how much difference is range important?

Here the boats that appear further away are 500 meters/yards closer.
The closest boat is .73nm from me, Eclipse is 1nm from me. So neither are far off at all.

You can only tell by electronics. Your eye is as stuffed as mine


Sent from a stupid phone that replaces words with weird stuff.

Not close enough to worry about mate..