‘Extremely complex’ salvage work sees OS35 stern section refloated

Works to remove the OS35 shipwreck off Catalan Bay are nearing completion after the stern section of the vessel was refloated and anchored by a team of salvors.

The OS35 vessel collided with an LNG tanker in British Gibraltar Territorial Waters last August, and this month salvors began work to lift two sections of the ship from the seabed.

The recent works mean the removal of the wreckage now in its final stages.

“We can see the stern section of the OS35 that has been refloated, stabilised, and is now anchored awaiting its final positioning onto the semi-submersible for departure,” the Captain of the Port, John Ghio, said.

Pumps on the top of the deck going into various compartments on the vessel allowed buoyancy to be re-established, a process Mr Ghio described as beingly “extremely complex”.

“It was an extremely complex situation, which the contractors have handled extremely well,” he said.

“At the end of the day it was always a challenge to re-establish buoyancy on a partial section of a ship which had been sunk because it had been involved in a collision.”

A storm during the winter months had split the ship before the team could do so manually as planned.

“The ship sections had broken apart and then it had suffered inevitable storm damage during the time that it has been here,” Mr Ghio said.

“So, all those things went towards complicating the job and making it a much more complex operation.”

“But again, a lot of planning, a lot of calculations, a lot of experts have been involved throughout and continue to be involved to make sure that we get to the point where we are now where we are almost there, and definitely we can say that the stern section has been done very successfully.”

It is estimated that within five working days with “suitable working conditions”, the wreckage will be ready to be placed on the semi-submersible just metres away in the bay.

These efforts will be temporarily halted due to bad weather expected over the course of this weekend.

“We are looking at an estimation of five full uninterrupted working days with suitable weather conditions.”

“That’s what we need right now.”

The ideal weather conditions are ones which see calm waters with a low swell.

“Because the forward section is going to be lifted mechanically, at that point when you are using chains to lift a very heavy piece of a ship and you have wave action it just adds an incredible amount of stress on the chains which potentially can cause it to snap or to damage the wreck.”

At times, contingency efforts have seen some 50 personnel involved in establishing buoyancy and anchoring the vessel.

“And those are salvaged professionals,” Mr Ghio said.

“So, it’s a very labour-intensive and human resources intensive operation.”

“Additionally, there’s been an oil spill response contingent brought it by the contractor, we have our own oil spill response personnel and we’ve brought additional personnel from OSRL in London.”

Mr Ghio told the Chronicle that avoiding any damage to the environment and marine life were an “integral part of the planning” in removing the wreckage.

“Those worries were always critical and they were an integral part of the planning that we put into the operation.”

He added that minimising such consequences have become easier compared to incidents such as the oil spillage in the winter months which was an unforeseen incident,

“I think the biggest difference now as opposed to what we saw over the winter is when the winter storms came we were having to take away our response measures and then we were subject to an unplanned incident taking place in terms of oil coming out, whereas now it is a planned operation.”

“So, what we do is pre-emptively we have a lot of means in place ready for a planned operation where we know at what point we have the biggest risk, so that we can be ready to cater for that risk.”

With the wreckage now buoyant and anchored, the next steps in the removal of the wreckage will involve placing the wreckage onto a semi-submersible vessel, which will then make its way to Amsterdam, Holland.

“The semi-submersible will then start working on sea fastening, which is making the two parts stable on top of the deck for its transit to Amsterdam.”

Once the wreckage is mounted onto the semi-submersible, the risk of pollution and damaging marine life will be eliminated.

“But that is something that the moment it is up on the semi-submersible and out of the water, our risk exposure is over,” Mr Ghio added.

He thanked members of the public for complying with the 600m exclusion zone and co-operation in allowing efforts to run smoothly.

Mr Ghio said: “I always have to thank the public for their patience and the fact that we’ve had zero instances of the general public interfering with the operation.”