Rescue Boat Fall Accidents: The Hidden Winch Defect an Annual Inspection Can Miss

A Boat That Fell With Three People Aboard

During a routine rescue boat drill aboard a tanker, the boat descended rapidly and uncontrolled, injuring three crewmembers. Germany's Federal Bureau of Maritime Casualty Investigation (BSU) traced the cause to a hidden technical defect inside the launching appliance's winch — specifically its freewheel unit (a one-way clutch that's supposed to let the boat lower under control and hold it once stopped). Corrosive ambient air and moisture had gotten into the winch and degraded the freewheel and braking components from the inside.

Why the Annual Inspection Didn't Catch It

This is the part worth sitting with: the equipment had passed its annual inspection. Japan P&I Club, publishing the case as loss-prevention guidance, was direct about why — internal deterioration of this kind “cannot be detected solely through routine visual inspections.” A freewheel module corroding from the inside doesn't necessarily look different from the outside. A boat, davit, and winch that look fine, and have a valid inspection certificate to prove it, can still be carrying a defect that only shows up the moment load and gravity test it for real — which on a rescue boat, that moment is a drill or a genuine emergency, with people aboard.

What Japan P&I Actually Recommends

• Go beyond the visual check. Periodic open-up inspections of the winch's internal freewheel and braking components, not just the annual survey's external/functional check.
• Replace on a schedule, not just on failure. Follow the manufacturer's recommended replacement intervals for critical internal parts — a component that's still technically working isn't the same as one that's still within its safe service life.
• Don't skip the pre-launch verification. Follow your SMS's pre-inspection and verification steps before launching a rescue boat with crew aboard, every time, not just when something feels off.
• Brief the failure mode, not just the drill steps. Run a hazard assessment before the drill that specifically assumes a machinery failure is possible, and share it in the toolbox talk — crew who know what an uncontrolled descent looks like and sounds like are faster to react if it starts.

The Wider Lesson

A passed inspection tells you a system met the check it was given. It doesn't tell you the check was capable of finding every failure mode the system has. Lifesaving appliances that combine mechanical load-bearing (winches, brakes, freewheel clutches) with corrosive marine environments are exactly where that gap matters most — because the one time the defect actually gets tested under full load is the one time you can't afford it to fail.

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Related Reading

• NO.2 Ocean Pioneer – this week's featured incident, another case where paperwork said a system was safe and it wasn't
• This week's full regulatory roundup