It took three years to gain acceptance for the provision, in crowded waters, of two parallel channels for the main traffic, each reserved for streams travelling in opposite directions. It then took another four years to obtain the corresponding marking in the Dover Strait, which served as a testing ground for the system. However, since this came into operation in 1967, there has been an amazingly rapid expansion of the organization of crowded waters. At a time when new schemes are being brought to the attention of seamen, it is important to take a close look at the authority which such regulations possess.