The UK MAIB issued report on the investigation into the listing, flooding and grounding of Hoegh Osaka in Bramble Bank, The Solent, UK on 3 January 2015. Stability modelling and analysis following the accident show that Hoegh Osaka heeled heavily to starboard while turning as a result of having departed port with inadequate stability.A key finding of the MAIB investigation is that no departure stability calculation had been carried out on completion of cargo operations and before Hoegh Osaka sailed.
The Incident
At 2109 on 3 January 2015, the pure car and truck carrier Hoegh Osaka was rounding West Bramble buoy in The Solent when it developed a significant starboard list causing some cargo shift and consequent flooding. With the list in excess of 40°, the ship lost steerage and propulsion, and subsequently drifted onto Bramble Bank, grounding at 2115.
Hoegh Osaka had sailed from the port of Southampton, bound for Bremerhaven, at 2006. A pilot was embarked and there were 24 crew on board. Following the accident, all crew were successfully evacuated from the ship or recovered from the surrounding waters. There was no pollution. A major salvage operation successfully refloated Hoegh Osaka and it was subsequently taken to a safe berth in Southampton on 22 January.
Stability modelling and analysis following the accident show that Hoegh Osaka heeled heavily to starboard while turning as a result of having departed port with inadequate stability. Cargo distribution was such that the upper vehicle decks were full while the lower vehicle decks were lightly loaded. Hoegh Osaka was low on bunker fuel oil, which was stored low down in the ship. With no additional ballast having been loaded prior to departure, the ship’s overall centre of gravity was relatively high. The analysis also concluded that it was most likely that the cargo shifted due to the ship’s excessive list and was not causal to the accident.
Hoegh Osaka’s itinerary had changed from its routine loading rotation between three north-west European ports. The actual cargo weight and stowage were significantly different from the final cargo tally supplied to the ship. Ballast tank quantities were estimated on board and differed significantly from actual tank levels. Cargo unit vertical centres of gravity were routinely not allowed for in the ship’s calculated stability condition. These factors all combined to result in the ship leaving Southampton with insufficient stability for the voyage
A key finding of the MAIB investigation is that no departure stability calculation had been carried out on completion of cargo operations and before Hoegh Osaka sailed. Witness and anecdotal evidence suggests that this practice extends to the car carrier sector in general. The fundamental requirements for establishing before departure that a ship has a suitable margin of stability for the intended voyage had been eroded on board Hoegh Osaka such that unsafe practices had become the norm.
Safety Issues
- The ship’s bow trim would have been detrimental to manoeuvring, and probably contributed to the high rate of turn.
- While the ship had positive stability on departure, it is estimated that its condition did not comply with IMO stability requirements.
- Hoegh Osaka’s actual cargo weight and stowage were significantly different to the final cargo tally supplied to the ship
- Hoegh Osaka’s ballast tank quantities were estimated by the chief officer and differed significantly from actual tank levels
- The pre-stowage cargo plans for the three north-west European ports were compiled by the port captain assuming the original itinerary, and remained unaltered after the itinerary had changed.
- Hoegh Osaka’s chief officer neither felt that he had the authority nor had the need to question the pre-stowage plan presented on this occasion.
- There were significant differences between the actual weight and the shipper’s declared weight with regard to several cargo units that had been loaded on board Hoegh Osaka
Learn more by reading the report herebelow
Source & Image Credit: UK MAIB
