The Yokohama Zone has been one of the major cable maintenance zones in the Asia-Pacific region. In 1997, it was reformed and developed having two ships standby throughout the years with the creation of "The Agreement for the Maintenance of Pacific Ocean Cable Systems in the Yokohama Zone" and was supplemented with the "Yokohama Zone ROV Agreement" in 2001.

The majority of the region's cables are maintained within this agreement which provides the security required for these important submarine cables.

When the original coaxial submarine cable systems were put into commercial service over 40 years ago, each cable owner contracted with a cable ship operator for the individual maintenance of its own cable.

View from Cable Ship's Bridge

As the number of new cable systems gradually increased, such a scheme of individual cable maintenance contracts became inadequate as a result of the limited availability of cable ships to provide the maintenance service.
With no clear rule among those maintained cables, there was a world wide needs for the cable owners to collaborate together to create a comprehensive agreement for the use of a cable ship between the relevant Maintenance Authorities (MAs) and ship operator.
This created the additional benefit of sharing the cost for a cable ship.

The result of this was the creation of a cable maintenance zone. Thus the Yokohama Zone (YZ) was established for the cables in Northern Asia and Northwest region of the Pacific. Adjacent to the YZ, we have North America Zone, the SEAIOCMA Zone and the Fiji Zone in the Asia-Pacific Region.

After the establishment of the YZ, it has continuously improved with the replacement of new ship, the introduction of ROVs and also a two-ship operation.

The cost of YZ ships and ROVs are on a fixed standing charge basis. Those charges are allocated with an accounting unit calculated by a formula agreed by MA. This method is a very fair and reasonable cost allocation method and enables the unit price to decrease when new cables enter the agreement.

YZ is one of the cable maintenance zones that is part of a mutual assistance charter called the Pacific and Indian Ocean Cable Maintenance Agreement. In the event of a major multiple failure of cables, a maintenance zone is able to obtain additional vessels from an adjacent Zone.

Beside of the above PIOCMA mutual assistance, YZ is continuously supported by two cable ships which are on standby within the zone.
The locations of the cable ships are well situated with the relevant depot service for the storage of spare cable and equipment enabling rapid action after formal request for mobilization by MA.
Also with the knowledge and cooperation of MAs, working permit for the repair operation can be obtained within reasonable timeframe. Also, emergency spare transportation of cable and equipment from one storage depot to another can be done in a timely manner should a shortage of spare submersible equipment arise.

Zone maintenance is a well proven solution to best scheme to maintain a submarine cable system, and the YZ is able to provide such a service.

For questions or requests for admission into the Zone, please contact with the Yokohama Zone chair.