Crossing the TSS - the answer

I'd long since stopped following that thread as it broke down into pedantry, but I'm surprised that it was necessary to seek official confirmation of that particular point. I thought everyone knew that it was ship's heading (and not course through water or over ground) that had to be at 90º. It's not a question that's been controversial before.

Pete
 
I can't see the cause of confusion - it's completely clear to me. Heading is the direction you are pointing, course is the direction you are traveling. I don't see that it needs umpteen pages of discussion to decide this. Obviously you need to make minor course changes to pass behind ships.
 
Thanks for that Graham.

Unfortunately I am probably one of many who thinks he knows the correct answer but as on these threads suddenly realised I did not know exactly the correct answer - eg whether I had to use the engine to assist, was obliged to use the engine assistance or accept its sensible to use engine assistance.

I am fortunate that S coast to France there is no TSS but there is a "stream" of ships that have exited one TSS and heading for the next TSS so they are unlikely to deviate much from their straight line course.

When I started I aimed to give big ships a wide berth but now find its better to be consistent and if I am the stand on vessel then stand on until I feel uncomfortable eg the bigs ships RADAR marpa may show we will miss but if the 200m miss is with me in front of his bows on CPA then I will deviate to go behind.

I do find it best to leave it as late as sensible though as I believe most ships make small course adjustments based on their marpa when far away!
 
MGN364 is a free download from the MCA about crossing TSS's although focuses on the Dover Strait.
Everyone planning to cross a TSS should read and digest (IMHO)
 
Sailfree said:
When I started I aimed to give big ships a wide berth but now find its better to be consistent and if I am the stand on vessel then stand on until I feel uncomfortable eg the bigs ships RADAR marpa may show we will miss but if the 200m miss is with me in front of his bows on CPA then I will deviate to go behind.

I do find it best to leave it as late as sensible though as I believe most ships make small course adjustments based on their marpa when far away!
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A stand on vessel needs to think very carefully in doing anything other than turning to starboard to the same heading as the ship; turning to port and slowing down are only permissible as an ultimate collision avoidance strategies, which should not happen often! The problem is this:

1. A yacht's wobbly marpa reading (unless one has a gyro compass) will not be very accurate, with the inaccuracy depending on the sea-state. Even a ship's marpa can be confused by the tiny radar profile of most yachts. A yacht's AIS (if fitted) is an infinitely better tool to see what the ship is doing, and yacht AIS transponders are more than helpful to ships.

2. At the point you become worried the ship may have already moved a few degrees to port; fine if executed before it became the stand-on vessel.

3. At the point you are thinking of going astern of the ship, the OOW will almost certainly be watching you like a hawk! In the situation you describe it is common practice to take a course of action, which is a tiny bit dubious - i.e. determine that at 200m CPA no collision risk exists and that he is entitled to make an additional small turn to port to widen the CPA to a safer 500m+. In these circumstances you will get away with either slowing down or turning to port.

4. But should the OOW determine that a collision risk exists, he will respond by turning hard to starboard. If you now turn to port and/or slow the ship will go max starboard with the appropriate sound signal. The ship cannot reverse this turn due to its massive turning inertia. A highly dangerous situation has unnecessarily been created! So sailors should think hard about dipping stand-on ships.
 
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pmagowan said:
+1
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I sought a definitive answer inspired by the original post. If the coastguard's information is derived from an AIS transmission, it may include the heading.

If, however, from a radar plot, how does he know the ship's heading? Does he do the sums with a knowledge of the tide or maybe a bit of computing wizardry does it for him?

My own attitude to these posts is that I refrain from chiding innocent views - we are not all experts on everything!
 
Graham_Wright said:
If, however, from a radar plot, how does he know the ship's heading? Does he do the sums with a knowledge of the tide or maybe a bit of computing wizardry does it for him?
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I suspect that in nearly all cases they don't worry about it. In the case of a radar target travelling at 45 degrees across the lane they'll check that its forward speed and the tidal stream combine to make a 90 degree heading plausible.

Pete
 
My penny's worth here is to note that on sailing down to the Med. in 2004 we had a few close encounters but on returning in 2009 with a radar transponder fitted (Seame) we had no problems.
On discussing this with a professional seaman he pointed out that the radar return from most yachts is insignificant and may not consistent enough to activate MARPA systems. The radar transponder does however give a strong return and if there is the possibility of a collision with a "stand-on" vessel, then the ship must take the best avoiding action it can. (The same comment would apply to an AIS transmission)
Obviously, restricted maneuverability should be taken into account but it can be very dangerous for the stand -on vessel to take evasive action such as slowing down or changing course as an avoidance plan based on an observed course and speed may already be in operation on the larger vessel.
There are firm rules...but stay flexible!
 
Graham_Wright said:
I sought a definitive answer inspired by the original post. If the coastguard's information is derived from an AIS transmission, it may include the heading.

If, however, from a radar plot, how does he know the ship's heading? Does he do the sums with a knowledge of the tide or maybe a bit of computing wizardry does it for him?

My own attitude to these posts is that I refrain from chiding innocent views - we are not all experts on everything!
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I am not chiding. It is quite alright if some people do not know something, as you say there is none of us who know everything. However, when you read the colregs the description seems to be in such a way as to make it very clear exactly what they mean. The term heading has a distinct meaning. If people don't know what it is then it is simply a matter of looking it up. You have got it clarified very clearly which saves others the effort.

There are loads of ways of the CG knowing that someone is disobeying colregs ranging from AIS, radar with calculations to show that it is unlikely that tide etc is the cause of the errant course, or even simply a call from a big ship saying 'there is some numpty driving all over the TSS like a dodgem car'. In any event, it should now be clear to everyone who reads your post that you need to stick your nose in the correct direction if possible.
 
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