Ports.com

YOKOSUKA

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:

• Vessel characteristics
• Berth and anchorage conditions
• Most recent tropical cyclone warning advisory
• Tropical cyclone climatology
• Sheltering or haven qualities

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 Department of Defense assets. Tropical cyclone and storm warnings for the waters around Japan originated by the Japan Meteorological Agency (JMA) can be obtained via the Naval Pacific Meteorology and Oceanography Center Yokosuka Typhoon Support web page (See References) or the JMA web site http://www.jma.go.jp/jma/indexe.html.

Commander, Naval Forces Japan (CNFJ), is the Condition of Readiness (COR) authority for Commander Fleet Activities Yokosuka (CFAY) and Sasebo (CFAS) including the associated residential, fuel, and ammunition storage sites, as well as Yokohama North Dock and Iwo Jima . Commander, Naval Forces Japan will set CORs for severe weather to include Tropical Cyclones (TCCORs) and Storms (Storm CORs). The Naval Pacific Meteorology and Oceanography Center (NPMOC) Yokosuka issues gale, storm, tropical storm, or typhoon warnings to indicate force and time of onset of destructive winds.

Conditions of Readiness have four distinct levels (IV-I). These levels are based on the following criteria: 1) speed of sustained winds 2) speed of wind gusts 3) the period of time prior to the forecast onset of damaging or destructive winds and gusts. Damaging wind is defined as sustained winds of 34-49 kt (40-56 mph) or frequent gusts of 40-59 kt 46-68 mph). Destructive wind is defined as sustained winds of 50 kt (58 mph) or greater, or gusts of 60 kt (69 mph) or greater. A TCCOR (Tropical Cyclone Condition of Readiness) is a special classification of COR that is used when dangerous or damaging winds are expected in association with a tropical cyclone or developing tropical cyclone.

TCCOR/Storm COR Levels are as follows:

1. TCCOR/Storm COR Storm Watch: The weather system is expected to pass dangerously close to the installation and any shift in track or increase in intensity may result in rapid elevations in CORs and destructive force winds occurring on short notice. At a minimum, sustained damaging force winds of 34-49 kt with significant higher gusts of up to 59 kt may be experienced when this condition is set.
2. TCCOR/Storm COR IV: Trend indicates a possible threat of destructive winds of the force indicated within 72 hours.
3. TCCOR/Storm COR III: Destructive winds of the force indicated are possible within 48 hours.
4. TCCOR/Storm COR II: Destructive winds of the force indicated are possible within 24 hours.
5. TCCOR/Storm COR I: Destructive winds of the force indicated are possible within 12 hours.
6. TCCOR/Storm COR 1 CAUTION: Sustained winds of 34-49 kt (39-56 mph) with frequent gusts of 50 to 59 kt (58-68 mph) are occurring at a particular location.
7. TCCOR/Storm COR 1 EMERGENCY: Sustained winds of 50 kt (58 mph) and up or frequent gusts 60 kt (69 mph) or greater are occurring at a particular installation.
8. TCCOR/Storm COR RECOVERY: When sustained winds fall below 50 kt and gusts of 60 kt or greater are no longer occurring.
9. TCCOR/Storm COR ALL CLEAR: The meteorological system has passed and the threat of severe weather is over and it is safe to go out doors.

The COMFLEACT Typhoon Command Center/Emergency Operations Center (TCC/EOC) will be manned at the setting of TCCOR IV, III, and II until such time as each COR is attained and reports have been made. TCC/EOC will be manned on a 24-hour basis upon setting of COR I and will secure after condition “ALL CLEAR” is set. The Port Control Dispatcher, FLEACT, Yokosuka will inform Fleet units of the setting of TCCOR conditions on 328.2 MHz. Port Control also monitors bridge to bridge Channel 10. TCCORs are also broadcast on the local TV on METOC Channel 13 and Base Channel 12 as well as over Eagle 810 radio. Additionally they are available on http://163.251.101.53/cgi-bin/main.pl?yoko. TCC/EOC can be reached at 243-1701/1774. Port Control, FLEACT, Yokosuka is at 243-7366. The CNFJ Command/Typhoon/Emergency net is on HF frequencies 9328.5, 4023.5, or 18398.5. A continuous tropical cyclone watch is set by Naval Pacific Meteorology and Oceanography Center Yokosuka whenever a tropical cyclone is forecast to come within 180 nmi of any CNFJ activity and can be reached at 243-5595.

The interpretation of tropical cyclone climatology is addressed in the following sections.

Evasion at Sea

With the exception of aircraft carriers, evasion at sea is not the recommended course of action for most Navy ships at anchorages or berths in the Port of Yokosuka. A strong wind is the most important factor to be considered. Wave action has only limited effect in the Port of Yokosuka and storm surge effects are negligible.

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), Pearl Harbor 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 Yokosuka from the southwest, the following guideline is offered: An evasion route to the southeast and crossing the T early enough to avoid the impact of building winds and seas and no later than 48 hours prior to the expected CPA of the approaching tropical cyclone.

In all cases, the timing of the evasion is affected by:

• The time required to make preparations to get underway
• The time required to reach open water and gain sea room
• The forward speed of the tropical cyclone
• The radius of hazardous winds and seas that can adversely impact a vessel's ability to reach open water.

A late departure from port may make the sortie difficult due to fishing boat congestion at the harbor entrance and increase the likelihood of encountering heavy weather as the ship departs Tokyo Bay. Additionally, local authorities state that the large number of Japanese fishing boats that move into Yokosuka Bay for shelter prior to typhoon passage severely restricts the ability of larger vessels from leaving (or entering) the port.

Each tropical storm or typhoon must be considered as differing from those preceding it. The accompanying synoptic situation must be fully understood. To blindly establish and follow one technique or rule for avoiding the storm's danger area is not practical. The Japanese say, "the only solution is that there is no one solution."

In general, the effects of wave/swell generated by a tropical cyclone initially will be encountered in the vicinity of Kannon Saki by departing ships (see Figure V-1 ) and may reduce the speed of advance (SOA) thereby increasing the time required to reach open sea. If a ship is caught in the wave/swell pattern ahead of a tropical cyclone, particularly 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 (see Figure V-48 ). If the typhoon is forecast to follow a recurving track, with a CPA to the east of Yokosuka , then a course downsea/downwind in the left or navigable semicircle may be advisable.

Any course to the north along the east coast of Honshu is considered unwise. The possibility of being overrun exists if the storm accelerates and/or turns suddenly to the north. The average speed of advance in the higher latitudes (30-40°N) of tropical cyclones is about 25 kt; however, they have been tracked as fast as 50 kt. Typhoon wind intensities tend to decrease as the system moves into the northern latitudes, but nevertheless can be quite destructive.

If a ship Captain makes the decision to evade at sea, plan to get underway well in advance of the storm's arrival. Port Operations stated during a site visit in November 2005 that Navy ships desiring to leave port would normally sortie at least 48 hours in advance of an approaching tropical cyclone. It must be remembered that tropical cyclones are notoriously difficult to accurately forecast, especially in the recurvature phase, and the 48-hour forecast position and intensity can be in error as occurred during Typhoon 26W Ma-On in 2004. A storm may be closer to or farther from Yokosuka than the forecast indicates, or right or left of the storm's forecast track.

Japanese Meteorological Agency officials reported during the Site Visit in November 2005 that a 2004 analysis/intercomparison of 9 forecast models for all tropical cyclones (BOM, ECMWF, UKMO, NCEP, DWD, CAC, JMA, CAN, and Meteo France ) indicated a bias to the southwest after recurvature of tropical cyclones south of Yokosuka, Japan. In other words, the analysis indicated models were moving the storms too slowly after recurvature.

The widely held doctrine of evasion at sea rather than remaining in port for the single purpose of minimizing typhoon- related damage is not generally recommended when in port at Yokosuka. In 1989 two large Navy ships were berthed at Berth 8 when a typhoon threatened the Yokosuka area. The one that was moored outboard chose to evade at sea, and suffered damage. All of the vessels that remained in port incurred no damage.

The JMSDF piers in the Port of Yokosuka (Y-1- Y-4) are vulnerable to high winds from a tropical cyclone. JMSDF ships use Tateyama Bay (Figure V-1 ) as a typhoon anchorage particularly when a typhoon is expected to pass east of Tokyo Bay. Water depths in Tateyama Bay are deep enough for vessels of all sizes and the bottom offers good holding. Kisarazu Harbor, also identified on Figure V-1, is also used.

Merchant vessels have at times, depending on the direction of the tropical storm or typhoon CPA, anchored in the following areas:

Tropical cyclone passage to the east or south of Tokyo Bay - anchor in Chiba Harbor or Kisarazu Harbor.

Tropical cyclone passage to the west or north of Tokyo Bay - anchor in Kaneda Bay.

The 3rd Regional Maritime Safety Headquarters issued a brochure in 1992 titled INFORMATION SERVICE FOR VESSELS AT ANCHOR IN TOKYO BAY IN THE EVENT OF A TYPHOON APPROACHING THE MAIN ISLAND OF HONSHU , that is relevant today. The following information has been excerpt from the brochure.

During the period when typhoons are approaching the main island of Honshu, Tokyo Bay anchorages tend to become overcrowded with vessels seeking shelter from the approaching bad weather. Overcrowding of anchorages during stormy weather can lead to the additional hazards of collisions and grounding due to anchor dragging. To prevent and reduce the risk of such accidents, the Tokyo Bay Traffic Advisory Service Center (Call sign TOKYO MARTIS) provides information services for vessels at anchor or seeking anchorage in Tokyo Bay. The Center airs information services broadcasts following advisory warnings to evacuate the port or harbor due to an approaching typhoon.

The brochure also makes the following recommendations to be taken during stormy weather:

(1) Maintain a listening watch on VHF Channel 16 or by radio on 1665 KHz.

(2) Listen for warnings on vessels that are dragging their anchors. The warnings will be broadcast on VHF Channel 12 following a general call on Channel 16.

(3) Keep a proper watch with sufficient lookouts. If necessary, main engines should be ready for immediate use. Power to windlasses should also be available for emergency use.

(4) Maintain a safe distance from other vessels and be alert for signs of anchor dragging either by your own vessel or others in the vicinity. Be aware that a sudden change of wind speed and direction may affect anchor-holding power.

(5) Take into account the depth of water and type of holding ground in the anchorage and if necessary use both anchors with sufficient scope of cable laid out. Main engines should be used to back-up the anchors if necessary.

(6) Improve the vessels sea-keeping qualities at anchor in order to reduce the risk of anchor(s) dragging. For example, vessels with large sail areas should consider such measures as taking on additional ballast, altering the vessels trim and use of main engines to prevent the vessel from dragging her anchor.

Vessels carrying a dangerous cargo must anchor as directed by the Japanese Maritime Safety Office.

Ships requiring a pilot to transit the Uraga Suido Traffic Route may be unable to secure pilot services if winds are greater than about 35 kt because pilots embark and debark from small motor launches.

Remaining in Port

Remaining in port is, in almost all instances, the recommended course of action when a tropical storm or typhoon threatens Yokosuka. Most berths and bollards are in good repair and a number of large, rubber " Yokohama " fenders are available to reduce the potential for damage to ships and piers. Prior to going into Typhoon Cyclone Condition of Readiness Three, nests of ships are broken up if at all possible. If any piers are empty, a berthing plan is prepared that will put ships in the most protected berths. Note that special mission ships or other ships from Yokohama normally sortie to Yokosuka and add to the port loading. Some of the smaller dry docks are flooded in order to store small craft, barges, donuts, pusherboats, tugs and pleasure craft. Port Ops and the Navy Harbor Pilots confirmed many of the following actions that should be considered when a tropical cyclone is approaching:

1. Berth reassignment, if necessary, should be accomplished before 20 kt winds begin. Ships with large sail areas should be assigned preferred berthing depending on the direction of the closest point of approach (CPA); i.e., if a typhoon is forecast to pass to the east, use berth 8, and use berth 12 if the forecast passage is to the west. Vessels should light off and secure shore power if at all possible. For conventional CV's, a shift to Dry Dock #6 is recommended when Tropical Cyclone Condition of Readiness Three is set for destructive winds of 50 kt sustained or greater, or gusts of 60 kt or greater. If a shift is not feasible, a sortie should be considered. Note that Drydock #6 was not available as of the Site Visit in November 2005.
2. Anchors should be placed under foot except in dry docks.
3. Extra attention should be given to the brow and mooring lines during the passage of the storm. Ships should relocate the brow as necessary, put out extra line and wire as deemed necessary and should be ready to tend mooring lines. Additional 6 and 8-inch nylon storm lines and spring lay wire ropes are available from Port Operations for heavy weather moorings. As indicated by Port Ops during the Site Visit in November 2005, ships need to follow NAVSEA requirements with regard to ship foul weather moorings. Rat guards and other flying objects should be removed or otherwise secured. Ships on vulnerable berths should have engines lit off and disconnect shore power. As stated in the Report on the allision involving the Vincennes , “Historic data indicates that max winds observed in Yokosuka harbor from typhoons can often be expected to be at or above the 64-kt limit for instituting heavy weather moorings as contrasted to storm moorings.” Note at the time of the allision that the Vincennes had both shafts tagged out, no heavy weather moorings or anchor under foot, and had a skeleton crew onboard. Additionally, a tug was not immediately available. It should also be noted that since that time many new procedures have been put in place, including revised Tropical Cyclone Conditions of Readiness, to prevent a reoccurrence of a similar incident.
4. Ships with large sail areas should consider having a tug stand by during the period of highest winds. Port Operations has pilots and tugs available for assistance. As of the Site Visit in November 2005, Port Ops has a procedure in place to stand up tug crews and have two pilots available when TCCOR conditions are set.
5. Although the rated holding strength of the mooring buoys inside the harbor is good, they are not the preferred location to be when strong winds are expected. Their exposure to northerly winds through the harbor entrance and orientation with respect to the surrounding landmasses does not give them the same protection, as do the pierside berths. Mooring buoys outside the harbor are unprotected from northerly winds and have only limited protection from southerly winds. As of the Site Visit in November 2005, Port Ops stated that mooring buoys could only be used for tugs and that the holding strength was suspect.
6. The anchorages within Yokosuka Bay have mud and sand bottoms with fair to good holding quality when enough chain is used, but can be impacted from northerly winds. Vessels using the anchorages should have engines in standby to ease the strain on the chain and to keep the anchor from dragging in moderate to strong wind situations. As of the Site Visit in November 2005, Port Ops stated that Anchorages A-1, A-10, A-11, A-12, and A-136 can be used by small Naval ships during tropical cyclones. Note that the USNS Yukon (T-AO 202), with a large wind sail area, grounded while anchored in Yokosuka Harbor (A11) on September 8, 2004. Heavy winds, with gusts to 45 knots from Tropical Sarika, moved the ship from its anchorage onto a soft mud bottom approximately 400 yards (366 m) away.
7. Flooding, caused by heavy precipitation, of the Fleet Activities land complex may occur; therefore, all ships should provide their own electrical power.

When there are many ships in port and only limited pierside facilities, a ship may elect to evade the typhoon at sea or anchor in Tokyo Bay .

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