Rules of the road...stand on vessel?

RichardS

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Rule 2 is a generalised statement of prudence. It essence, it says that there is an over riding responsibility placed on all mariners to avoid collisions even when that avoiding action would not be in compliance with the other rules. So what? Generally, if you are the stand on vessel, you should hold your course and allow the stand off vessel to make a course change to avoid collision. However, if it become apparent that the stand off vessel is not going to change course, then the stand on vessel must take action to avoid the collision.

When in a small vessel as stand on, I watch larger stand off vessels closely for changes of course. I assess the likelyhood of their ability to make a significant course change before getting too close for comfort and will, if necessary, take avoiding action based on what I can see. That is in accordance with Rule 2. In other words, give the stand off vessel time and space to comply with the rules but be prepared to take avoiding action if they fail to make a course change to avoid you. There's no point in maintaining a rigid adherence to the rules as you disappear under a tankers bow.

I don't recall hearing the term "stand off" vessel before. I use the term "give way" vessel.

Is "stand off" the official ColRegs term?

Richard
 

rob2

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Must be your feminine side exposing itself.

Not a pretty sight!

I was mulling over the number of times (pre-AIS, not that I have one) that I've wished to call a ship on VHF and the call goes along the lines of "Large, black ship in position ####, heading###..." There is obviously a risk of talking to the wrong ship, so it really matters to confirm identity before basing any decisions on the subsequent conversation. The two factors I consider most important is to identify something truly distinctive about the vessel's appearance and to transmit on LOW power so as not to alert every bored watch keeper in a thirty mile radius and invite them in for a chat! Of course, if a ship is heading toward you you can absolutely guarantee that you cannot read it's name as this only appears on the stern! Who thought that one up? Why not emblazon the name across the front of the bridge? Anyway, quite often I couldn't guess how to pronounce the name so that the Russian radio operator would recognize his own name!

Rob.
 

BrianH

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I was mulling over the number of times (pre-AIS, not that I have one) that I've wished to call a ship on VHF and the call goes along the lines of "Large, black ship in position ####, heading###..." There is obviously a risk of talking to the wrong ship, so it really matters to confirm identity before basing any decisions on the subsequent conversation.
One of the advantages of AIS that even a modest receiver can give. Below is the screen shot of the incident referred to in my post above. Cut off to the left of the target list is the name of the ship (top line, highlighted) to protect the guilty. Armed with the name I could call on channel 16 when distance was under 1nm and less than 2 minutes to a potential collision. Actually, the course was wavering implying a less than attentive helmsperson, supported by the abrupt change to starboard as soon as my call went out.

When I first posted this some years ago there was plenty of those who read chapter and verse at me about never needing to resort to VHF, that MCA guidelines specify not to do so, that ships have everything under control and that my target would have safely passed to my port side anyway. Even a deck officer criticised me for calling, saying he never answered such calls. Well, they weren't there and I was ... and I would do it again.

Crisimage02.jpg

 

prv

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Seriously though, most of the ships I see do have the name on either bow. Though how readable from dead ahead and some distance I'm not sure.

Even if not the vessel name, a number of them have the name of the shipping line in very large letters on the side. So you could call "CMA CGM vessel at..." if you really needed to.

AIS renders the issue moot for an increasing number of us, though.

Pete
 

Leighb

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There is a lot of mention of the benefits of AIS, which I definitely endorse, however there is a huge difference in CPA of 0.5Nm behind the ship rather than ahead. :eek:
On my system at least, NASA Engine with data displayed on Standard Horizon plotter, I can find no way of distinguishing the two situations.
Do other AIS/Plotter combinations give more detail?
 

ex-Gladys

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My Garmin AIS/Plotter combo give me two options in the alarm settings; CPA and TCA (time to CPA). The alarm settings can be set to both, so in crowded waters I have CPA at 800m and TCA to 6 minutes, and off the Essex coast a couple of weeks back, a wind farm boat came hammering out of Brightlingsea at whatever, the alarm went off with nothing in site, except for the symbol just nudging up behind us... So the short answer to is yes.... Other set ups do work differently
 

Leighb

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My Garmin AIS/Plotter combo give me two options in the alarm settings; CPA and TCA (time to CPA). The alarm settings can be set to both, so in crowded waters I have CPA at 800m and TCA to 6 minutes, and off the Essex coast a couple of weeks back, a wind farm boat came hammering out of Brightlingsea at whatever, the alarm went off with nothing in site, except for the symbol just nudging up behind us... So the short answer to is yes.... Other set ups do work differently

Mine has time to CPA also, and the alarms, but does not show whether CPA will be ahead or astern of the other vessel. With radar one can work that out, but not as far as I can see with AIS.
 

fisherman

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Last week I heard a local FV calling a yacht to point out that he was fishing and asking to be avoided, the yacht, American accent, asked him to turn on his AIS. Over-reliance on tech.
 

ex-Gladys

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Mine has time to CPA also, and the alarms, but does not show whether CPA will be ahead or astern of the other vessel. With radar one can work that out, but not as far as I can see with AIS.

For alerts the Garmin shows the projected track of the vessel causing the alarm... I would guess this is down to the plotter interpretation and display of the appropriate parts of the NMEA VDM sentence
 

lpdsn

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Mine has time to CPA also, and the alarms, but does not show whether CPA will be ahead or astern of the other vessel. With radar one can work that out, but not as far as I can see with AIS.

All the necessary information is there in the AIS sentences, it's just a matter of what the receiving system does with it. (By receiving system I mean the one that receives the NMEA sentences from the AIS receiver.)
 

prv

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Mine has time to CPA also, and the alarms, but does not show whether CPA will be ahead or astern of the other vessel. With radar one can work that out, but not as far as I can see with AIS.

My AIS display draws a little plan of what the CPA situation will look like if both vessels maintain their course and speed. No working out required, just press a button.

I'm told that OpenCPN provides the same information by drawing predicted tracks on the main chart from the target and the "own vessel" marker, lengths proportional to speeds and ending at the CPA time/position.

Many AIS displays built into plotters etc are deficient in the information they provide and the manner in which they present it, but that's not a failing of the protocol per se. All the data is available if the designer can be bothered to use it properly.

Pete
 

BrianH

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I'm told that OpenCPN provides the same information by drawing predicted tracks on the main chart from the target and the "own vessel" marker, lengths proportional to speeds and ending at the CPA time/position.
To confirm what you have been told here is again the screen snapshot of my situation two days ago from OpenCPN running on an Acer Aspire netbook. The two blue dots show the extrapolated positions, the dotted line between them the CPA. On aesthetic grounds I don't much like the comic-book graphic used to highlight the threat vessel.

Not shown is the overlaid window that is automatically presented as soon as the pre-set criteria are crossed with all the threat ship's details including CPA and TCPA. An alarm also sounds that can be silenced for that threat.

AIS 13.jpg
 

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