Firm towing Transocean Winner had no storms contingency plan
The company responsible for towing a rig that ran aground on the Isle of Lewis had "no contingency plan" for stormy weather that was encountered.
ALP had tasked one if its tugs with moving Transocean Winner from Norway to the Mediterranean in August last year.
Gale force winds hit the towing operation off the Scottish coast.
An investigation into the grounding highlighted the lack of a contingency plan and also found the tow line was in a poor condition.
Wind and sea conditions were so severe that the tug, ALP Forward, and the 17,000 tonne rig were driven backwards for 24 hours before the main tow line broke.
For a time, while it was still attached to the tow line and tug, there were concerns the rig would run aground on the Flannan Islands, according to the Marine Accident Investigation Branch (MAIB).
But later, after the tug and rig were shifted by the conditions into another position, the tow line broke and Transocean Winner was driven on to rocks at Dalmore near Carloway early on 8 August.
The grounding led to 12,000 gallons of diesel oil leaking from the rig. The fuel dispersed and did not cause a pollution hazard, according to agencies involved in salvaging the rig.
Over the course of two months, Transocean Winner was moved from the beach before being towed to a more sheltered anchorage off Lewis where it could be loaded on to Hawk, a semi submersible ship.
The rig was then transported to a yard in Turkey, where it had been originally bound, after a stopover at Malta, and was scrapped.
In its report, the MAIB said the Met Office had forecast strong winds for 6 August. However, the towing operation is understood to have been planned around a more favourable outlook.
The towing manual, the document setting out the operation "did not contain any contingency plan for adverse weather or refer to suitable shelter", said the MAIB.
It also said no ports of refuge had been identified for the north-west coast of Scotland.
The MAIB said the main tow line was in a poor condition and was likely to have deteriorated further was it was stretched by the weight and motion of the rig during the storm..
Investigators also said that once Transocean Winner had broken free of the tow there was nothing that could have been done to stop it running aground.
The MAIB examined whether an emergency tug based in Kirkwall in Orkney could have averted the grounding.
But investigators said: "It is very unlikely that it would have been able to provide any practical assistance in maintaining control of Transocean Winner."
ALP Maritime Services BV said it was reviewing the findings in the MAIB's report.
The company said: "This will take some time and we will be able to comment once the review has been completed.
"For ALP Maritime health and safety management are the hallmarks of its worldwide activities and central to its methods of operations.
"ALP Maritime endeavours to identify and eliminate foreseeable hazards and to minimise the likelihood and impact of incidents which may cause personal injury, illness, and damage to the environment."
Transocean said it was grateful to all those who provided assistance during the episode and said the rig was dismantled earlier this year.
The company said it has been regularly monitoring the site where the rig grounded and had found no sign of pollution.