Relevant documents and M-notices: MSN 1781, MGN 364
Rule 10 applies to all vessels navigating in or near a TSS. There are a lot of parts to this rule but they are all fairly straightforward. Unlike narrow channels in Rule 9, there is a definition of what a Traffic separation scheme (henceforth referred to as a TSS) is. This is given, in a roundabout way, in Rule 10 (a):
Rule 10 (a)
This Rule applies to traffic separation schemes adopted by the Organisation and does not relieve any vessel of her obligation under any other rule.
The organisation mentioned in this rule is the International Maritime Organisation (IMO). This reiterates part of Rule 1 (d) ‘Traffic separation schemes may be adopted by the Organisation for the purpose of these Rules.')
How to tell if a TSS is IMO adopted
The definitive list of IMO adopted TSSs is found in IMO publication ‘Ships Routeing’ They are also found in Notice to Mariners No 17 of the Annual Summary.
What about on charts?
TSSs that have been adopted by the IMO are shown in exactly the same way on Admiralty charts as those that have been established by national authorities.
From Admiralty notice 17:
Charts not only show the IMO-adopted routeing measures but also those routeing measures established by coastal states or other competent national authorities concerned with the safety of navigation. On the charts, the IMO-adopted schemes are not normally differentiated from the other routeing schemes; the portrayal of national traffic separation schemes on charts available from the ADMIRALTY chart series is solely for the safety and convenience of shipping and implies no recognition of the international validity of the relevant regulations.
I’d expect the 2/O, during their passage planning, to have marked on the chart where a TSS was IMO adopted, and I’d expect it to have been brought up in the pre-voyage meeting. This answer will please your examiner as it shows that you’re thinking about passage planning in a joined-up way.
What about on an ECDIS?
On an ECDIS it is possible to use the ‘picker’ tool to interrogate a TSS and see if it is IMO adopted.
An examiner may ask you to give some examples of IMO adopted TSSs round the UK:
Approaches to the Humber
Sunk and approaches to the Thames
Approaches to Hook of Holland
West Hinder
Dover Strait
Off Casquets
Off Lands End, between Seven Stones and Longships
South of the Isles of Scilly
West of the Isles of Scilly
Off Fastnet Rock
Off Smalls
Off Tuskar Rock
Off Skerries
In Liverpool Bay
In the North Channel
Off Neist Point
Some nationally adopted TSSs will have requirements for certain classes of vessel; these may be mentioned on the chart, but check local sailing directions. This shouldn’t have any bearing on COLREGs, so don’t worry about this in regards to Rule 10.
…and does not relieve any vessel of her obligation under any other rule.
Rule 10 only stipulates certain aspects of behaviour and some impeding obligations. Nothing in Rule 10 changes which vessel is the give-way/stand-on vessel in a situation where risk of collision exists.
Rule 10 (b)
A vessel using a traffic separation scheme shall:
(i) proceed in the appropriate traffic lane in the general direction of traffic flow for that lane;
(ii) so far as practicable keep clear of a traffic separation line or separation zone;
(iii) normally join or leave a traffic lane at the termination of the lane, but when joining or leaving from either side shall do so at as small an angle to the general direction of traffic flow as practicable.
A vessel using a traffic separation scheme shall:
A vessel crossing a TSS is not using it. Only vessels navigating along the lanes are using it. Shall, as we’ve seen in previous articles in this series, means there is an obligation to do something.
proceed in the appropriate traffic lane in the general direction of traffic flow for that lane
The lanes of a TSS are marked on the chart, as are separation zones. On Admiralty charts the separation zone is shaded in purple, and separation lines are shown by an intermittent purple line. Within each lane there will be arrows with a solid purple line as their border, showing the mandatory direction of traffic flow. Note that an arrow with a broken purple border indicates a non-mandatory direction of traffic flow.
Breaking Rule 10 (b)(i) comes with financial penalties. From the MCA prosecutions 2012:
On 24 March 2012 the vessel ‘Jolly Fisherman’ was monitored by Dover Coastguard travelling in a North Easterly direction in the South West lane of the Dover Strait Traffic Separation Scheme (TSS), contrary to Rule 10(b)(i) of the Convention on the International Regulations for Preventing Collisions at Sea 1972…The vessel travelled 17 miles in the wrong direction in the Dover Strait TSS. Penalty: Was fined £7500 plus costs of £2254.
This is under The Merchant Shipping (Distress Signals and Prevention of Collisions) Regulations 1996 Regulation 6:
…in the case of any infringement of Rule 10(b)(i) (duty to proceed with traffic flow in lanes of separation schemes) of the International Regulations (being an offence corresponding to an offence under section 419(2) of the Merchant Shipping Act 1894) by a fine not exceeding £50,000
If you sight a vessel going the wrong way down a TSS the appropriate signal to let them know would be ‘YG’, meaning ‘You appear not to be complying with the TSS’. If you receive this signal (by flags, flashing light of a ships whistle) check your course and position immediately and take action to remedy the situation.
so far as practicable keep clear of a traffic separation line or separation zone
So far as practicable means that, if you are forced to cross a separation line or enter a separation zone to avoid a risk of collision then it is acceptable to do so.
normally join or leave a traffic lane at the termination of the lane
The terminations of the lane might be a long way from where you are, though, so it is acceptable to join or leave midway along a TSS.
but when joining or leaving from either side shall do so at as small an angle to the general direction of traffic flow as practicable.
This is to make it clear that your intention is to join the TSS rather than to cross it. Which brings us to:
Rule 10 (c)
A vessel shall, so far as practicable, avoid crossing traffic lanes but if obliged to do so shall cross on a heading as nearly as practicable at right angles to the general direction of traffic flow.
A vessel shall, so far as practicable, avoid crossing traffic lanes
If you can go around the TSS, that’s the preferred option. As to ‘so far as practicable’, that’s harder to judge; if a ship can steam 20 miles to go round a TSS, or 3 miles to cross it and end up in the same place, is that practicable?