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FREMANTLE

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 remaining in port? Evasion rationale should include consideration of the following general factors:

1. Vessel characteristics
2. Berth and anchorage conditions
3. Most recent tropical cyclone 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 Perth Tropical Warning Center. The interpretation of tropical cyclone climatology is addressed in the following sections.

Evasion at Sea

Evasion at sea is the recommended course of action for all ships anchored in Gage Roads and Fremantle Inner Harbor. Carriers would most likely be anchored in Gage Roads and should sortie in the event of an approaching tropical cyclone. Smaller combatants also have the option, if time is available, to move to more sheltered anchorage locations in Cockburn Sound or use the safer Port of Stirling berths or mooring locations. Evasion at sea is not the recommended course of action for ships at anchorages or protected berths in Cockburn Sound.

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 cyclone 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!

Keeping in mind that tropical cyclones normally approach the Port of Fremantle from the northwest, the following guideline is offered: An evasion route to the west-southwest would provide following wind and sea for almost all approaching tropical cyclone situations.

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.

Remaining in Port

Remaining in port is not the recommended course of action for ships anchored in Gage Roads or berthed in the Inner Harbor. Berths E, F, G, and H in the Inner Harbor would be the preferred berths if a ship decided to remain in the Port and Port Authorities recommend that vessels put an anchor down at these berths during storm warnings. It should be noted that the berths in the Inner Harbor do not have adequate fenders for use during a tropical cyclone. The Cockburn Sound anchorage area and the Port of Stirling berths and mooring buoys provide excellent shelter from the effects of tropical cyclones affecting Fremantle. Vessels may be required by the Harbor Master to shift to a preferred berth or anchorage that would be dependent on the forecast wind directions as the cyclone approached. Vessels may also shift from an anchorage in Gage Roads or from the Fremantle Inner Harbor to a berth or mooring buoy in Stirling or to an anchorage in Cockburn Sound in the event of a tropical cyclone threat. Note that the channels through Success Bank and Parmelia Bank can be difficult to navigate during strong winds.

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