November 1997 Abandoned submarine cables
Maritime New Zealand is alerting seafarers to the existence of abandoned power and telecommunications cables that could snag fishing nets or anchors.
Information on submarine cables
Live cables are marked on charts, and must be avoided.
Abandoned cables are not always marked and can be found in most parts of New Zealand especially where power or telecommunications links have been established to islands or remote peninsulas. These cables were often laid across bays in areas where sea transport was well established prior to roads becoming established.
Even while in service, these now abandoned cables were sometimes difficult to locate for repairs, as they tended to sink into the seabed, or shift in strong currents. When repairs were made, faulty sections were cut out and dropped overboard, adding to the cable debris scattered in many areas.
Abandoned cables are still not easy to locate and are usually found by accident, old records having been lost or destroyed. Even where records still exist, they could be inaccurate. A number of cables were not laid in their intended positions because of tide and wind movement while they were being laid.
Safe practice tips
Seafarers should be aware that if an anchor or net is snagged, it may have come fast on an abandoned cable and they should take action which does not jeopardise the safety of their vessel. Where steps are taken to clear fouled anchors or nets, it should be assumed that the cable is ‘live’. The cable should not be cut but hung-off with a synthetic or natural fibre rope and lowered back on to the seabed.
Any incidents should be reported to the nearest Maritime Safety Inspector in order that the position of such a cable may be promulgated to all seafarers through Notices to Mariners. Charts should also be kept corrected and up-to-date with the latest information from Notices to Mariners.
Original source content - Boat Notice 141997, November: Abandoned submarine cables.