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MACKAY

THE DECISION TO SORTIE OR REMAIN IN PORT

General

Under normal circumstances, the decision on whether to sortie or remain in port is largely based on the answer to a single question: Would the vessel in question be better off attempting an evasion at sea or by remaining in port? In the case of Mackay, however, remaining in port is not an option because local harbor authorities state that Mackay Harbor is not a safe anchorage in a cyclone. Consequently, ships are instructed by the Mackay Port Authority to leave the harbor whenever the Bureau of Meteorology issues a "Cyclone Warning" for a coastal area that includes Mackay.

Evasion rationale should include consideration of the following general factors:

1. Vessel characteristics
2. Berth and anchorage conditions
3. Most recent hurricane warning advisory
4. Tropical cyclone climatology

Individual vessel characteristics and berth/anchorage conditions are best determined by those responsible for each vessel and local port authorities. Tropical cyclone warnings are issued by the Naval Pacific Meteorology and Oceanography Center/Joint Typhoon Warning Center Pearl harbor for the U.S. Government and by the Australian Bureau of Meteorology Brisbane Tropical Warning Center. The interpretation of tropical cyclone climatology is addressed in the following sections.

Evasion at Sea

It is the recommendation of this evaluation that all U.S. Navy ships sortie from the Port of Mackay at the first indication that Mackay will be threatened by an approaching tropical cyclone. Because of the orientation of the coast of Queensland and the existence of the Great Barrier Reef, sortie options are limited. In all sortie cases, the timing of the evasion is affected by:

1. The time required to make preparations to get underway.
2. The time required to reach open water and gain sea room.
3. The forward speed of the tropical cyclone.
4. The radius of hazardous winds and seas that can adversely impact a vessel's ability to reach open water and proceed on an evasion route.

Commanding officers and ship masters with access to tropical cyclone warnings and advisories coupled with OTSR services are most capable of making the safest and most prudent decision for successful storm evasion and avoidance. In all sortie situations, OTSR services from Naval Pacific Meteorology and Oceanography Center (NPMOC), Yokosuka should be requested and utilized. The best sortie route in a specific tropical scenario is largely dependent on the location of the tropical cyclone and the forecast track. During any tropical cyclone threat there is normally one to three options available to the commanding officer and ship master. Selection of the best option is the objective of all concerned!

For Mackay the following guidelines are offered:

a. Tropical cyclone approaching from northeast or east.

Sortie as early as possible and steam southward into deep water via Capricorn Channel.

b. Tropical cyclone approaching from north, northwest or west.

Sortie as early as possible and steam northeastward via Hydrographers Passage (pilot required) or southward (no pilot required), placing as much distance as possible between the sortieing unit and the tropical cyclone. The vessel could be placed on the dangerous left side of the storm's circulation, so adequate clearancee is necessary to avoid the storm's worst effects.

Remaining in Port

The Port of Mackay is not considered to be a safe place for a ship to be berthed during a tropical cyclone passage. The Mackay Port Authority states that ships would be ordered to evacuate from the port whenever an approaching tropical cyclone threatens the port, so remaining in port is not an option. It is the recommendation of this evaluation that all U.S. Navy ships sortie from the Port well in advance of an approaching tropical cyclone and not wait the order to put to sea.

Source: http://www.nrlmry.navy.mil/port_studies/thh-nc/australi/mackay/text/sect8.htm