Rules 9 & 10 — Narrow Channels and TSS

Rule 9 requires a vessel proceeding along a narrow channel or fairway to keep as near the starboard outer limit as is safe and practicable. A vessel under 20 metres or a sailing vessel must not impede a vessel that can safely navigate only within the channel. A vessel must not cross if the crossing would impede such a vessel, and overtaking or bend signals and local directions may also apply.

Rule 10 applies to IMO-adopted traffic separation schemes and does not relieve any vessel of another rule. A vessel using a lane proceeds in the general direction of traffic flow and normally joins or leaves at a lane termination; joining or leaving from a side is done at as small an angle to the traffic direction as practicable. A vessel should avoid crossing, but when obliged to cross does so on a heading—as distinct from course over ground—as nearly as practicable at right angles to the general traffic flow.

Vessels following a traffic lane do not automatically have priority over crossing vessels. The ordinary steering and sailing rules still decide collision encounters. At the same time, a sailing vessel or vessel under 20 metres must not impede the safe passage of a power-driven vessel following the lane, so the crossing should be planned early enough not to force lane traffic to deviate course or speed.

The Inshore Traffic Zone rule has explicit categories and purposes. Vessels under 20 metres, sailing vessels and vessels engaged in fishing may use it; other vessels may use it for the listed access purposes or immediate danger. Do not turn the general 'use the lane when safe' wording into a blanket ban on small-yacht ITZ use, and check current chart notes and MCA routeing guidance for the particular scheme.