TheDecisiontoEvadeorRemaininPort
KAGOSHIMA
THE DECISION TO EVADE OR REMAIN IN PORT
Evasion Rationale
Because of the threat of high winds associated with tropical cyclones and the extremely poor holding quality of the bottom (sand and shale) in the anchorage, Kagoshima Harbor IS NOT CONSIDERED A SAFE TYPHOON HAVEN. Commanding Officers and Masters of vessels must recognize the inherent dangers that exist when exposed to hazardous weather and remaining at an anchorage which has known poor holding qualities.
(At the Nippon Oil Staging Terminal located at Kiire, all pumping from oil tankers is ceased when sustained winds reach 30 kt. When sustained winds reach gale force intensity, ship's masters are advised to leave the terminal and depart the area, preferably to the open sea.)
Figures V-86, V-87, V-88, V-89, through V-90 show the tropical cyclone threat axis for Kagoshima from June-October. The area of the arrows represent approximately a 30% or greater probability of a tropical cyclone coming within 180 n mi of Kagoshima.
For general information on tropical cyclone warnings the reader is referred to Chapter I.
Evasion
In the southern part of Japan there are two areas that have been evaluated as typhoon havens -- Sasebo in northwestern Kyushu (Rudolph, 1975), and the Kure/Iwakuni area in Hiroshima Bay (Manning, 1975). (Sasebo Harbor is considered an excellent haven but only for vessels smaller than aircraft carriers.)
Since transit time, whether it be to another port or to sea, may be lengthy, evasion must commence early. To facilitate early action, the following time table (in conjunction with Figures V-86, V-87, V-88, V-89, to V-90) has been constructed.
1. An existing tropical cyclone moves into or development takes place in Area A with forecast movement toward Kyushu:
a. Review material condition of ship. Evasion may be desirable 2-4 days hence. Begin planning course of action to be taken in case of increasing threat.
b. Reconsider any maintenance that would render the ship incapable of getting underway within 48 hours.
2. Tropical cyclone enters Area B with forecast movement toward Kagoshima:
a. Execute evasion plans made in previous steps. Evasion should be completed before storm enters Area C. If evasion is to be made to Sasebo, approximately one-half day's steaming time. the commanding officer may elect to delay execution of evasion plans accordingly.
3. Tropical cyclone enters Area C moving toward Kagoshima:
a. If evasion is not accomplished by this time, evasion from Kagoshima Bay is no longer recommended. If the decision to remain at anchor is made, ensure sufficient power is made available to counter high winds and seas by steaming to the anchor.
b. Another course of action would be to get way on the ship. and place the ship's head into the wind and sea. Since Kagoshima Bay is large, and with few exceptions deep, the ship can be placed in various locations in the bay to reduce the fetch and thereby reduce the effects of wave action. Movement into the southwestern part of the bay would tend to offset the effects of southeasterly winds. It is not recommended that a ship be placed in the northern regions of Kagoshima Bay, north of Sakurajima, due to the restrictive nature of the area and the shallow water in the middle of this region. (It should be noted that of all the tropical cyclones studied, the longest duration of gale force winds at Kagoshima was 5 hours.)
Evasion routes at sea may be developed by the use of the warnings received from FWC/JTWC and Appendix 1-A (the mean tropical cyclone tracks, track limits, and average speed of movements for the months June-October) in conjunction with Figures V-86, V-87, V-88, V-89, to V-90 (tropical cyclone threat axis and approach times to Kagoshima for the months June-October). In all cases, Optimum Track Ship Routing (OTSR) should be consulted as to the best evasion route. Ships whose ultimate destination is the eastern Pacific may want to consider evading to Yokosuka in south central Honshu (Graff, 1975).
In general, the effects of sea/swell generated by a tropical cyclone may reduce the speed of advance (SOA) thereby increasing the time required to reach the open sea. If a ship is caught in the sea/swell pattern ahead of an intense tropical storm or typhoon, the SOA may be reduced to the point that the ship will be unable to maneuver to clear the danger area.
There are two basic evasion tactics. The most common among civilian shipping companies is to place the ship south of the tropical cyclone in the navigable semicircle. The other is to proceed north into the Yellow Sea or Sea of Japan.
In the latter case, the cooler surface water and cool air found at higher latitudes cause a weakening and ultimate dissipation of the tropical cyclone. Therefore, a ship should experience less difficulty in riding out a storm at these latitudes than if it steamed south to seek the navigable semicircle and encountered winds in excess of 80 kt enroute.
Source: http://www.nrlmry.navy.mil/port_studies/thh-nc/japan/kagoshim/text/sect5.htm
