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Accidents

Biter (2023)

The tug Biter girted, capsized and sank while assisting the passenger vessel Hebridean Princess off Greenock on 24 February 2023. Both crew members died, and Biter was later declared a total constructive loss.

Classification

  • Incident Type: Capsize girding
  • Severity: High
  • Investigation Body: MAIB

Vessel Details

FieldValue
Vessel NameBiter
Vessel NamesBiter / Hebridean Princess
Vessel TypeTug
Flag StateUnited Kingdom [GB]
Gross Tonnage28.7
LOA (m)16.25
Year Built1982
Crew Size2

Incident Details

FieldValue
Date2023-02-24
LocationOff Greenock, Scotland
RegionUnited Kingdom
Coordinates55.9500, -4.7700
Fatalities2
Injuries0
Missing0
Vessels Lost1
Direct DamageTotal constructive loss of Biter; no damage to Hebridean Princess.
OutcomeBiter girted, capsized and sank while assisting Hebridean Princess; both crew members died and the tug became a total constructive loss.

Key facts

  • Biter girted and capsized at about 15:27 UTC while attached to the stern of Hebridean Princess during the passenger vessel’s approach to James Watt Dock.
  • The tug could not reverse into a safe astern position before load came onto its towing bridle, and the gob rope did not prevent sideways towing.
  • Hebridean Princess was making about 4.6 knots, producing towline loads between two and five times those at the port’s recommended lower speed range.
  • Biter sank at about 16:02 UTC, and Police Scotland divers recovered both crew members from the wheelhouse on 25 February 2023.
  • Biter was later declared a total constructive loss; Hebridean Princess was not damaged.

Narrative

On 24 February 2023, Hebridean Princess returned towards James Watt Dock, Greenock, after engine and equipment trials. The passenger vessel was assisted by Biter forward and the ASD tug Wrestler aft during its earlier departure, and Biter was allocated to assist aft during the return manoeuvre. Biter’s crew boarded the tug at about 14:30 and proceeded towards the Clyde navigational channel.

At 15:15, Hebridean Princess entered the channel at about 6 knots over the ground. Biter approached and passed its twin-line bridle to the passenger vessel’s aft mooring party. The pilot subsequently reduced the passenger vessel’s speed, and Biter’s bridle was made fast at about 15:18. Four minutes later, with Hebridean Princess still making about 4.5 knots, the pilot directed Biter to operate directly astern after the forward tug Bruiser had made fast.

At 15:26:40, Biter turned to starboard and peeled away from Hebridean Princess’s side. The manoeuvre was not complete when the starboard bridle became taut at 15:26:58. The tug’s turn stopped with its heading about 45 degrees to the right of the passenger vessel’s track, and the bridle pulled Biter sideways. The tug heeled to port and capsized at 15:27:08. The rapid capsize left insufficient time for the crew to operate the emergency tow release.

Hebridean Princess’s crew released the tug lines, reported the casualty and launched rescue craft. By 15:39, several rescue vessels were at the scene. Biter began to list while inverted at about 15:55 and sank at 16:02. A diver later observed a body in the wheelhouse, but conditions made immediate recovery unsafe. Police Scotland divers recovered both crew members from the wheelhouse on 25 February. Biter was salvaged in March and declared a total constructive loss by its insurers. Hebridean Princess sustained no damage.

The MAIB found that Biter could not reverse into an astern position before its weight came onto the bridle and that the gob rope did not prevent sideways towing. The passenger vessel’s speed substantially increased towline loading. The investigation also identified incomplete pilot and tug information exchanges, weaknesses in tug-operation training and the open accommodation hatch, which compromised watertight integrity after inversion.

Sequence of events

Date/timeEvent
2023-02-24 14:30 UTCBiter’s crew boarded the tug and proceeded towards the Clyde navigational channel.
2023-02-24 15:15 UTCHebridean Princess entered the channel at about 6 knots over the ground.
2023-02-24 15:18 UTCBiter’s bridle was made fast to the passenger vessel’s stern.
2023-02-24 15:26 UTCAfter Bruiser made fast forward, the pilot ordered Biter to operate directly astern.
2023-02-24 15:26:58 UTCThe starboard bridle became taut as Biter’s turn stalled.
2023-02-24 15:27:08 UTCBiter girted and capsized.
2023-02-24 16:02 UTCBiter sank.
2023-02-25Police Scotland divers recovered both crew members from the wheelhouse.

Contributing factors

FactorEvidence statusDescription
Incomplete astern manoeuvreConfirmed findingBiter had not reversed into position astern before its weight came onto the towing bridle.
Gob-rope performanceConfirmed findingThe gob rope did not prevent the tug from being towed sideways; the report could not determine exactly why it rendered.
Assisted-vessel speedConfirmed findingHebridean Princess’s speed of about 4.6 knots produced towline loads between two and five times those at the recommended lower speed range.
Pilot and tug information exchangeConfirmed findingThe information exchange did not give the tug masters a timely opportunity to influence the plan for their employment.
Open accommodation hatchConfirmed findingThe open hatch compromised watertight integrity and reduced the likelihood of an air pocket after the tug inverted.

Investigation

The Marine Accident Investigation Branch investigated the very serious marine casualty and published its report in November 2024. It concluded that Biter girted and capsized because it could not reverse direction before load came onto the towing bridle and the gob rope did not prevent sideways towing. The report made recommendations on tug-operation procedures and training, pilot and tug information exchanges, tug selection, AIS carriage and testing of gob ropes and towlines.

References

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