Pipework, Valves, and 45 Minutes: What the Loss of Opportune Tells Every Fishing Vessel About Flooding

36 Miles East of Lerwick, 24 March 2024

At approximately 0445, Opportune’s mate went to the engine room to investigate a bilge alarm. Before reaching the bottom of the ladder, he found water at gearbox level — spray coming off the tailshaft as it rotated, water originating from below the floor plates. He immediately informed the skipper.

When they returned together minutes later, the engine room was filled with white odourless vapour. Almost certainly steam: floodwater meeting the hot engine and exhaust. It was unsafe to enter.

From that point, there was nothing the crew could do to stop the flood. The sea inlet valves were below the floor plates — already submerged. The bilge pumps could only be started from inside the engine room. The space was inaccessible.

At 0458, the mate operated the DSC distress alert. At approximately 0530, Opportune sank by the stern, 36 nautical miles east of Lerwick. All eight crew were rescued by UK and Norwegian coastguard helicopters. Not one was injured. The vessel was a total loss.

What the Investigation Found

The Source of the Flood

The definitive cause could not be established — the wreck lies in over 100 metres of water and was not examined. But the investigation systematically eliminated the alternatives. Hull plating was in good condition at the last survey. The tailshaft was still turning when the flood was discovered, ruling out catastrophic shaft failure. Sea valves had been overhauled in August 2023. That left the seawater pipework.

Opportune’s main suction system ran on 200mm diameter galvanised mild steel pipe, with 150mm and 125mm branches feeding the engine cooling system and electric bilge/deck wash pumps. The RNLI estimates that failure of a 177.8mm pipe produces approximately 8 tonnes of water per minute. Opportune’s main pipework was larger. The rate of flooding — from bilge alarm at 0445 to loss of propulsion and power by approximately 0500 — is consistent with a large-diameter pipe failure.

Some of this pipework may have been in place since Opportune was built in Spain in 1998. MCA Surveyor Advice Note 29 (SAN 29), published in 2016, is explicit: galvanised steel seawater piping is expected to be replaced at least once over a 20-year vessel life. But SAN 29 was an internal MCA document. It had not been incorporated into MSIS 27 — the published instructions to surveyors. Fishing vessel owners had no access to it. There is no record that the MCA applied SAN 29 requirements during Opportune’s 2022 renewal survey.

The Sea Inlet Valves

Closing the sea inlet valves was the crew’s only realistic option to contain a pipework flood. Opportune’s valves were located below the engine room floor plates, operated through hinged flaps using portable extension spindles stored nearby. The floor plates carried no markings showing valve positions. No diagram was posted near the engine room entrance.

This arrangement — acceptable under MSN 1872(F) Amendment 1 for existing vessels, provided ‘rapid and practical means’ of operation are available — becomes useless the moment the floor is covered with floodwater. By the time the bilge alarm was investigated, the water was already at gearbox level.

This is not a new lesson. Audacious sank in 2012 with the same design feature. Chloe T sank in the same year for the same reason. The combined investigation led to SAN 29. Eight years later, Opportune was lost to the same failure mode.

The Bilge Pumps

Opportune had two electric bilge pumps with a combined rated capacity of 50m³ per hour. Both could only be started from within the engine room. With the space inaccessible, neither could be operated. And even if they had been running continuously, 50m³/hr against an estimated 480t/hr ingress rate would have made no practical difference.

The vessel also carried a portable diesel salvage pump — stowed in the fish processing space, heavy, requiring two crew to move and deploy. It was not used.

The SMS

Opportune’s safety folder was compiled using the SafetyFolder online platform. It contained 52 risk assessments — including one for sea inlet valve failure. It did not contain a risk assessment for seawater pipework failure. It did not contain a flood action plan. It did not include flooding in the monthly drill programme. There were no plans showing the location of bilge pump controls or sea inlet valves posted near the engine room entrances.

MSN 1872(F) Amendment 1 Chapter 8 requires monthly drills including flooding scenarios. MGN 570(F) Amendment No.1 provides detailed guidance. The Fishermen’s Safety Guide provides a flood action plan template. MGN 165(F) explicitly recommends that a sea inlet valve location diagram is displayed near the engine room. None of this was in place.

What If?

What if the 2022 renewal survey had required a pipework condition assessment? The MCA surveyor noted that the hull was in good condition for its age and that sea valves had been overhauled — but recorded nothing about seawater pipework condition. The Report of Hull Condition had no section for pipework. SAN 29 required owners of vessels over 10 years old to provide a pipework diagram and evidence of pressure testing or thickness measurement — but SAN 29 was not part of the public-facing survey framework. Had it been, an assessment 16 months before the loss might have identified the risk.

What if the August 2023 grounding repair had included a full pipework inspection? When Opportune was slipped for the post-grounding tailshaft repair, the owner commissioned a local contractor to inspect the engine room pipework. Some sections were removed, cleaned, and inspected. The main ring under the floor plates was left in place and power-washed. A complete removal and inspection might have found the section that later failed — or might not. What is certain is that the main pipework ring received less scrutiny than the sections that could be reached.