Basslink loses 20 days to bad weather in repairing subsea cable

The subsea cable bringing high-speed communications and energy to Tasmanians will not be repaired until late June thanks to poor weather conditions.

Basslink has provided a progress update on its subsea cable repairs, saying it has lost more than 20 days to inclement weather since completing the first joint, with the repair timeframe pushed out to late June.

"More than 20 days have been lost to weather since the first joint was completed," Basslink said in a statement on Tuesday.

"Given the repair has around 20 days of marine-based work remaining, which will be directly affected by any changes in weather conditions, Basslink needs to allow for additional contingency in the timeline for the cable's return to service.

"As a result, Basslink has advised Hydro Tasmania and the Tasmanian government that the anticipated return to service date is now late June.

"Once all the joints have been completed, it is anticipated that Basslink will return to full operations within a week."

Basslink's repair vessel arrived at the fault location on Friday May 20, with the first two days spent finishing work to be able to lay the cable bight. The cable splicing for the next joint is expected to begin on Tuesday with more favourable weather conditions.

In mid April, Basslink had said it would require six days of consecutive clear weather to repair each of the three joints in order to complete repairs on its subsea cable providing energy and wholesale high-speed telecommunications services to Tasmania.

"As the jointing works take place on the deck of the vessel and are highly susceptible to weather conditions, each joint will require a window of relatively calm sea conditions and clear weather for six continuous days to allow such works to be completed safely," Basslink said last month.

"Bad weather or rough sea state can damage the cable, result in abortive jointing works, or pose unnecessary occupational, health, and safety risks for the repair crew. The jointing works are highly complex, and will see the three lengths of new cables (ie, the high voltage cable, the metallic return cable and the fibre optic cable) joined to the existing cables and bundled together, before being laid on the seabed."

The Basslink Interconnector, the world's second-longest subsea cable, has been down since December, leaving many Tasmanians without energy and internet services.

In late March, Basslink revealed that excess water damage into its cable would result in repairs not being completed until mid-June. Prior to this, Basslink had said repairs would be done by late May.

The fault in the cable was discovered 90.5km from the Tasmanian coastline and removed and capped on Easter Sunday, three months after going down.

Upon completion of the jointing work, the cable will be laid in the trench and on the seabed, where it will sink naturally.