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The Thirtieth Berth: What PS Waverley Hitting Brodick Pier Tells Every Ship's Engineer About Known Failure Modes

🕑 5 min read words Safety • Incident

Brodick, Isle of Arran, 3 September 2020 — 1640

The afternoon excursion had gone well. PS Waverley — the world's last seagoing paddle steamer — had taken 186 passengers down the Arran coast and was returning to Brodick pier. The vessel had berthed here 29 times before. The approach was familiar. The chief engineer had been at the controls during the berthing the previous week.

At 1640, Waverley entered Brodick Bay making 13 knots. The master briefed the quartermaster: enter the bay, shape a course to the eastern berth at the closed end of the pier, apply a 10° port turn in the final approach. Standard procedure.

At approximately 100 metres from the concrete wall at the closed end of the pier, Waverley was travelling at 7.3 knots. The master ordered slow astern. The chief engineer (C/E), manually controlling the engine from the engine room below, stopped the engine. He moved the controls to the astern position. The engine did not restart.

The high-pressure piston had stopped at dead centre — the full extent of its travel. Steam could not flow through the engine in either direction. The vessel was still moving toward the pier at over 7 knots.

What Dead Centre Means on a Triple-Expansion Steam Engine

Waverley is propelled by an inclined triple-expansion steam reciprocating engine built by Rankin & Blackmore in Greenock in 1947. It drives two feathering paddle wheels via three pistons connected to a single crankshaft. There are no lateral thrusters. The vessel's turning circle is 548 metres — almost three cable lengths for a 73-metre vessel. She can stop in her own length from 16 knots when the paddle wheels are put to full astern. But she cannot do anything without propulsion.

If the high-pressure piston stops at the top of its travel — dead centre — steam cannot act on it in either direction. The engine is locked. The recovery technique is to admit impulse steam to the medium-pressure or low-pressure cylinder to nudge the crankshaft, moving the HP piston off dead centre, and then restart normally.

The C/E was aware this could happen. It had happened once before, in open water, with no danger. He applied the impulse steam technique to the MP cylinder. The crankshaft did not move.

The master ordered half astern. Full astern. Double full astern — an emergency command achieved by ordering full astern twice in rapid succession. None of these could be executed while the HP piston was at dead centre. The engine was locked.

The C/E eventually admitted steam to the HP cylinder in the ahead direction to shift the piston, and then restarted the engine in the astern direction. The paddle wheels began to turn astern. Waverley was decelerating.

At 1646, the bow struck the concrete structure at the closed end of the pier at 2.8 knots. No warning had been broadcast to passengers. Many were standing on the open Promenade Deck and Aft Boat Deck, watching the arrival.

The Impact

When Waverley struck the pier, passengers who were standing were thrown forward. They fell onto the deck, made contact with fixtures and fittings, hit railings. Twenty-one passengers and three crew required treatment. Three people suffered serious back and pelvis injuries. Two were evacuated by helicopter to a mainland hospital. Nine more were taken to the island's hospital. Waverley's bow was buckled inward, with three holes in the bow plating above the waterline.

No-one was killed. The vessel remained afloat. By any measure, the outcome could have been worse.

What the Investigation Found

The Defect That Made It Harder

In the post-accident inspection on 15 December 2020, investigators found that the locking nuts securing the HP piston valve to its rod were loose. This extended the piston valve's travel by 5.4% — advancing the engine's timing and causing excessive steam to enter the HP cylinder ahead of top dead centre. On an inclined engine this provides 'cushioning' of the piston when it approaches top dead centre, which directly counteracts the impulse steam technique for dead centre recovery.

The C/E almost certainly did not know this. The defect meant the standard recovery technique — which would normally work — was operating against a significant mechanical resistance it was not expected to face.

Why the Defect Was There

In 2016 and 2017, most of Waverley's experienced engineering personnel left the company. The outgoing C/E left handover notes — which were then lost during a further turnover of senior personnel. In 2015, the vessel's piston valve rings had been replaced with rings made from the wrong material because the correct specification was unknown; the original rings had to be reinstalled while the correct material was researched. The accumulated engineering knowledge that kept Waverley's complex machinery running correctly had been held in people, not in systems.

By 2020 the vessel had qualified but less vessel-specific engineers. They had not been trained in Waverley's specific dead centre failure mode. The PMS was still being developed. The maintenance records were dispersed, incomplete, and not standardised. The vessel was operating under an Interim Safety Management Certificate.

The loose locking nuts were a product of four years of maintenance knowledge degradation. Nobody had set out to leave them loose. Nobody had a documented procedure that would have identified them as a critical maintenance item requiring verification at each season start.

Why No Procedure Existed

The ISM Code requires companies to identify equipment whose sudden operational failure may result in hazardous situations, and to establish measures promoting reliability and managing those situations. Dead centre events were known and occasional — they had occurred once, in open water, with no consequences. They had never been assessed for their impact in a closed-end pier approach, which removes all recovery options except the propulsion system.

The MAIB found: 'The potential for Waverley's HP piston to stop at dead centre was a known possibility that had not been effectively risk assessed.' The procedure for managing it was held in the memory of experienced engineers, not in the SMS. When those engineers left, the procedure left with them.

The Closed End of the Pier

A closed-end berth terminates in a structure at right angles to the berth. A vessel cannot overshoot. Waverley has no lateral thrusters and a 548-metre turning circle. For a vessel with manual steam engine control, the approach to a closed-end berth is the worst possible scenario for propulsion failure: there is no recovery option except the engine.

No berth-specific risk assessment existed for Brodick's closed-end pier. The arrival plan described the normal procedure. There was no contingency for what to do if the engine failed to respond within the final 100 metres.

The Passengers Who Were Standing

High-speed passenger ferries routinely instruct passengers to remain seated during berthing. The impact on Waverley would have injured fewer people had passengers been seated and holding on. The MAIB noted that an assessment of closed-end berths might have identified those with elevated risk of a low-warning impact and prompted a standing precaution.

What If?

What if the dead centre event had been formally risk assessed? The risk assessment would have identified closed-end berths as the critical scenario. A contingency procedure would have existed. The C/E would have been trained in it. The response, when the event occurred, would have been faster and more decisive — possibly fast enough to prevent contact.

What if the locking nuts had been correctly maintained? The engine timing would have been correct. The impulse steam technique would have worked as designed. The C/E would have moved the HP piston off dead centre, restarted astern propulsion, and Waverley would have stopped in the berth normally.

What if the engineering knowledge had been captured before 2016? A documented PMS with clear specifications for every critical component would have kept the valve rod correctly adjusted. The maintenance procedures would have survived the staff change. The C/E in 2020 would have had a complete, vessel-specific training record for dead centre events.

For Chief Engineers and Engineers

Every complex propulsion system has known failure modes. Some of them are rare enough that they have never been formally trained for — instead passed down as 'watch out for this' from experienced to new crew. That system works as long as the experienced crew are present. The day they leave, the knowledge becomes inaccessible to anyone who needs it.

The ISM Code is not administration. It is a system designed to make critical knowledge survive staff turnover. If a failure mode you know about is not in the SMS — not risk assessed, not procedurised, not trained — it only exists as long as you do. Write it down.

For Masters

Passage planning extends to the approach and berthing. SOLAS Chapter V requires it. For every closed-end berth, the plan should include: minimum abort distance, propulsion contingency, and what action is taken if the engine fails to respond within the critical distance. 'It's never failed before' is not a contingency plan — it is a description of the 29 successful approaches before the 30th one.

Vessel Checklist

Known failure modes: Are all known propulsion, steering, and machinery failure modes formally documented in the SMS and risk-assessed in worst-case operational scenarios?
Critical manoeuvre contingencies: For closed-end berths, locks, and constrained approaches — is there a documented response for propulsion failure at each critical point?
Passage planning completeness: Do passage plans include the approach to and berthing at the destination, not just the ocean passage?
Maintenance documentation: If your most experienced engineer left tomorrow, would the PMS contain everything needed to maintain critical components correctly?
Competency documentation: For specialist vessel systems, are crew competencies formally assessed and recorded — not just assumed from experience?
Passenger safety during berthing: For berths where a rapid or unexpected impact is foreseeable, is there a standing procedure for passengers to be seated and holding on?

Test Your Knowledge

Try an engineering and SMS knowledge check at Crew Connect — ISM Code, propulsion contingencies, and passage planning questions from this investigation.