With respect to Article 6.33, the competent authorities may prescribe that a vessel carrying the boatmaster of a convoy shall sound two long blasts.
Note by the secretariat:
In accordance with article 9.07, paragraph 14, the following administrations prescribe that a vessel carrying the boatmaster of a convoy shall sound two long blasts:
1. Bulgaria;
2 Czech Republic;
3. Serbia;
4. Slovakia;
5. Turkey.