TSS Clarification

[TiggerToo]

While our summer cruise, we crossed (several) Traffic Separation Schemes.

In order to refresh our memories, we looked (again) at the IRPCS and I became a little confused. Can anyone here shed some light on this matter?

Rule 10 (a) states: "This rule applies... and does not relieve any vessel of her obligation under any other rule"

Rule 10 (j) states: "A vessel of less that 20m in length or a sailing vessel shall not impede the safe passage of a power vessel following a traffic lane"

What does "not impede" mean? We were crossing the TSS (on a 90o heading across them). According to rule 10(a) we would be a stand-on vessel if on a collision course with a power-driven vessel. But 10(j) states that we should not "impede". Common sense suggested that she keep well away of the Big Ships running down the TSS (we did this by slowing down, to pass behind). Was that the right thing to do?

 

[Sticky Fingers]

My understanding is that 10j trumps 10a, ie regardless of sail vs power, you are effectively the give way vessel, and thus are obliged to take action to avoid. Common sense and good seamanship would support that notion.

 

[AngusMcDoon]

Do not enter a TSS where you know that you will be a stand on vessel to an approaching vessel using the TSS and a conflict will occur. That's impeding because you made the choice for the risk of collision to happen. Wait outside the TSS for an attempt at a crossing where you will not be getting in anyone's way. Make it clear that you are not entering the TSS while you are waiting by moving parallel to or away from the TSS. When wanting to cross a busy TSS like the Maas estuary you may be told to wait at a holding point and given the go ahead to cross from VTS. That absolves you from rule 10j.

If once in the TSS a vessel appears with a risk of collision that you could not anticipate you may be the stand on vessel, so hold your course if that's the case.

 

[AngusMcDoon]

My understanding is that 10j trumps 10a, ie regardless of sail vs power, you are effectively the give way vessel, and thus are obliged to take action to avoid.

It doesn't. Rule 10a is clear...

and does not relieve any vessel of her obligation under any other rule

The good seamanship is not to impede, a decision taken before you enter the TSS.

One thing helms of ships hate is unpredictability from wafi's. They can see the CPA from ARPA or AIS (or changing bearing if they're oldies) and prefer you to hold your course so they can make a safe manoeuvre just the once if a conflict arises. The changes that can be made by ships are often slight and difficult to detect without electronic aids. To the helm on the ship 200m CPA seems fine - to the helm of a 10m sailing boat it seems offaly close. AIS, even receive only, helps a lot with this situation.

 

[Sticky Fingers]

Fair enough. The fact that it’s not abundantly clear suggests that the words could do with a review.

 

[AngusMcDoon]

Fair enough. The fact that it’s not abundantly clear suggests that the words could do with a review.

I completely agree. It took the harbour master at Portrush, a retired master mariner, to explain it to me clearly. The whole COLREGs is due for a review which I believe I've heard is in the offing, but as it's a UN thing it will take a long time to happen. I can't imagine Russia agreeing to anything at the moment.

 

[B27]

I'll admit to being a bit rusty about the finer points.

The ship is required to give way to some crossing vessels, which are required not to be there impeding the ship.

The rule is a sentence or two, to properly understand it means knowing a ton of case law.

Simple guide, Don't create situations where the ship is give way vessel

I think in many/most TSS situations, a ship can keep clear without 'being impeded'. e.g. by making a small alteration of course within its lane?

 

[AngusMcDoon]

The ship is required to give way to some crossing vessels, which are required not to be there impeding the ship.

Normal stand on-give way rules apply once in the TSS. Rule 10a. You can't predict every conflict from outside the TSS, for example a ship changing course to avoid another ship and then comes in conflict with you.

The rule is a sentence or two, to properly understand it means knowing a ton of case law.

I don't agree. Once you know the meaning of impede I have been given it's all clear and sensible. What's missing is the definition of impede. It would only take a sentence.

Simple guide, Don't create situations where the ship is give way vessel

Taking that course of action before you enter the TSS, which the rules require small craft to do, is following rule 10j. If you're in the TSS and it happens you are required to stand on, but that of course is not always easy to do.

I think in many/most TSS situations, a ship can keep clear without 'being impeded'. e.g. by making a small alteration of course within its lane?

In that case where does the boundary between impeding and not impeding occur? If that ship needs to make a 5 degree course change, or 5 knots off the speed, have you impeded it? It wouldn't be clear. The definition I obtained from Portrush HM is clear. The ambiguity is all down to the lack of clarity in the current COLREG's.

 

[Pye_End]

The critical word is 'safe'. You must not impede the SAFE passage...

That means that you must not force a ship to make a manoeuvre that will put it or someone else in danger. It does not say that you 'must not impede it's progress', else it would say exactly that.

 

[AngusMcDoon]

The critical word is 'safe'. You must not impede the SAFE passage...

I don't put your importance on safe here. The word appears throughout the COLREG's. It's our duty at all times, TSS or not, not to manoeuvre in a manner that puts any other vessel in danger.

 

[B27]

I suspect one could find ten retired professional mariners and get eleven conflicting definitions of 'impede' in this context.

I am not convinced that a sailing vessel's obligation to 'not impede' ends the moment they commit to entering the traffic lane.

I think it is entirely possible that our obligation to 'not impede...' might sometimes mean we should not enter TSS lanes.
Don't forget that there may be several ships in the lane with obligations to avoid one another.

 

[Pye_End]

I don't put your importance on safe here. The word appears throughout the COLREG's. It's our duty at all times, TSS or not, not to manoeuvre in a manner that puts any other vessel in danger.

If you look, for example, at rule 8 f, there is a clear distinction between 'impede the passage', and 'impede the safe passage'. It looks to me that the rules are very carefully written, and that if a word is there, then it is meant to be there. A quick skim through some of the rules, and I can't immediately find 'safe' somewhere used loosely, though there is plenty more (unless you can point in that direction?).

Realising 'safe' is used in that sentence does bring a certain clarity to the meaning that has previously been rather aloof whenever discussed before on here.

 

[Supertramp]

I would avoid a TSS if I can. But crossing at 90 degrees and timing or acting to avoid others is a sensible approach.

It gets harder in bad conditions when for example you can't lay a 90 degree course, or slowing down is not easy or desirable either. I use AIS which really helps seeing what others are doing and my first approach is to hold course and speed at least until its clear what another vessel is doing. Often other large vessels will slightly alter course to avoid close contact, even in TSS. Call on VHF if in doubt (but again you need AIS to identify the vessel).

 

[B27]

A 'safe passage' might not be the quickest, most convenient passage?
Or the course which the master of the vessel 'not to be impeded' had in mind?

 

[Pye_End]

A 'safe passage' might not be the quickest, most convenient passage?
Or the course which the master of the vessel 'not to be impeded' had in mind?

COLREGS don't really have a view on the time it takes to get to your destination. It's more concerned about making sure you get there at all!

 

[AngusMcDoon]

I am not convinced that a sailing vessel's obligation to 'not impede' ends the moment they commit to entering the traffic lane.

I think it is entirely possible that our obligation to 'not impede...' might sometimes mean we should not enter TSS lanes.
Don't forget that there may be several ships in the lane with obligations to avoid one another.

No, it doesn't. Within the TSS being stand on and changing your course or speed to put you in conflict with a ship following the TSS where no risk of conflict existed would also be impeding, but is an obviously daft thing to do, so I haven't mentioned that action so far.

I have never heard it suggested that a small craft should not cross a TSS at all. Crossing just outside the end of a busy TSS would cause the ships following the TSS even more bother as the small craft is now under no obligation not to impede.

 

[Pye_End]

Often other large vessels will slightly alter course to avoid close contact, even in TSS. Call on VHF if in doubt (but again you need AIS to identify the vessel).

Big ships obay the rules - simple as that. If they are required to avoid you, 95% of the time they will, and make alterations considerably earlier than you would deem necesssary on a small boat. It has been said by professional mariners that really want us to obay the rules as well - it makes our behaviour so much more predictable.

Crossing TSS's generally are pretty straight forward. You know the direction of travel, which makes it easier. If you get a train of half a dozen in a row then you might need to make some decisions about how to get through them, but so long as you are sensible it is fine. Just look at the numbers - how many small boats get mown down in TSS's? If loads and loads of rubber ducks driven by non-mariners, and swimmers, can get across the Channel (the busiest shipping lane etc. according to the media), then us sailors should have no trouble.

 

[Sticky Fingers]

Yes that’s all true. The Q was about the interpretation of the word “impede”. Not sure I’m 100% clear on that yet.

 

[B27]

No, it doesn't. Within the TSS being stand on and changing your course or speed to put you in conflict with a ship following the TSS where no risk of conflict existed would also be impeding, but is an obviously daft thing to do, so I haven't mentioned that action so far.

I have never heard it suggested that a small craft should not cross a TSS at all. Crossing just outside the end of a busy TSS would cause the ships following the TSS even more bother as the small craft is now under no obligation not to impede.

Races like the Fastnet tend to make TSSs exclusion zones.

 

[Pye_End]

Races like the Fastnet tend to make TSSs exclusion zones.

Probably because certain racers have a history of abusing the traffic lane.