1. Vessels may turn only after making certain that the movements of other vessels will allow them to do so safely, and without obliging such other vessels to change their course or speed abruptly.
2. If the intended manoeuvre will oblige other vessels to change their course or speed, the vessel wishing to turn shall, before turning, announce its intention in good time by sounding:
(a) A long blast followed by a short blast if it wishes to turn to starboard; or
(b) A long blast followed by two short blasts if it wishes to turn to port.
3. The other vessels shall, so far as is necessary and possible, change their speed and course to allow the turn to be made safely. In particular, when vessels wish to turn in order to head against the current, the other vessels shall help to ensure that they can do so in good time.
4. The provisions of paragraphs 1 to 3 above shall not apply to small craft in relation to other vessels. For small craft among themselves, only paragraphs 1 and 3 shall apply.
5. All turning is prohibited on sections marked with the prohibitory sign A.8 (annex 7). On the other hand, if sections of a waterway are marked with the informative sign E.8 (annex 7), boatmasters are recommended to choose such sections for turning, to which manoeuvre the provisions of this article remain applicable.