How to navigate your small yacht in a Traffic Separation Scheme (TSS)

24 November 2020

Rule 10 of COLREGS advises that a Traffic Separation Scheme may be adopted by the IMO for the purpose of the COLREGS. Rule 10(a) confirms that the rest of Rule 10 applies to an adopted Traffic Separation Scheme, but this does not relieve a vessel of her obligations under any other Rule. However, not all Traffic Separation Schemes are adopted. 

To confirm if a particular scheme is adopted, reference should be made to remarks on the appropriate chart, sailing directions and the United Kingdom’s Annual Summary of Notices to Mariners.

For sailors of vessels under 20 metres, the rules relating to TSS are fairly straightforward. First of all, though, it’s important to understand the difference between what might be referred to as a shipping lane and a designated TSS. 

A shipping lane may just be an area where shipping is plentiful, for example before and after TSS where ships are lining up to enter it. It might also be an area where shipping naturally congregates either because it is on a straight line between two points (such as headlands) which ships choose as the shortest route, or because they are designated routes in almanacs and on routing charts.

Sailing vessels are allowed to enter a TSS but they are required to cross as close as possible to a heading that is perpendicular to the travel of the ships in the TSS. Note two things, firstly, the requirement is to have a HEADING perpendicular, not a course. This is so that you cross the TSS as quickly as possible. The second point is that if you are sailing and the wind direction makes crossing at a heading perpendicular to the TSS then you may have to sail at a less desirable angle when crossing.

Sailing vessels crossing a TSS are required to not hinder shipping within a TSS and so the usual rules under COLREGS are different although a TSS does not give any other ‘rights of way’ to any other vessel. All vessels are still required to maintain a proper lookout and avoid a collision, so a skipper’s usual responsibilities under COLREGS still apply.

When crossing a TSS in poor visibility it is, one would hope, common sense to make sure you have your radar reflector fitted and if it is active, make sure it’s switched on. Maintain a radar watch is you have one and monitor AIS and appropriate VHF channels for the area, including channel 16. Listen for and transmit appropriate sound signals.

TSS are monitored by VTS and if you breach the rules for navigating a TSS you can expect to be called and possibly disciplined. You have been warned.

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