EntranceChannel
CAIRNS
ENTRANCE CHANNEL
The approximately 6 nmi long, 295 ft (90 m) wide Entrance Channel is oriented 209°14'/029°14' for most of its length (Figure XI-23). Its heading changes to 193°/013° approximately 0.75 nmi north of the mouth of Trinity Inlet. The channel is maintained at 27.2 ft (8.3 m). Mud flats are exposed adjacent to the channel during low tide. The beacons that mark the channel are 623 ft (190 m) apart, but the channel itself is only 295 ft (90 m) wide. Consequently, the outer edge of the channel is approximately 164 ft (50 m) inside the beacon positions.
The Cairns Port Authority requires under-keel clearances of 3 ft (0.9 m) for vessels under 30,000 tons in the Entrance Channel, and 2.0 ft (0.6 m) in the harbor. Vessels of 30,000 tons or greater displacement require a minimum under-keel clearance of 3.3 ft (1.0 m), except that for very large vessels, such as cruise ships, as much as 4.9 to 6.6 ft (1.5 to 2.0 m) may be required.
Source: http://www.nrlmry.navy.mil/port_studies/thh-nc/australi/cairns/text/sect3.htm
