Flooding of a port ballast tank along with structural deficiencies have been cited as causes for the loss of the converted ore carrier Stellar Daisy which sank while on a laden voyage from Brazil to Qingdao on 31 March 2017 with the loss of 22 lives. There were two survivors from the incident.
The marine safety investigation conducted by the Republic of the Marshall Islands Maritime Administrator determined that the likely direct cause of the ship’s foundering was a rapid list to port following a catastrophic structural failure of the ship’s hull that resulted in a loss of buoyancy and uncontrolled flooding.
According to the report, the structural failure and flooding are thought to have begun in the No. 2 port water ballast tank (WBT) and then progressed rapidly to include structural failure and flooding in multiple WBTs, voids, and cargo holds. The structural damage was likely due to a combination of factors, including the strength of the ship’s structure being compromised over time due to material fatigue, corrosion, unidentified structural defects, multi-port loading, and the forces imposed on the hull as a result of the weather conditions the ship encountered between 29–31 March 2017.
The Administrator’s marine safety investigation also concluded that the likely causal factors include:
- the large port and starboard wing tanks increased the potential for a major structural failure and loss of buoyancy in the event that one or more of these tanks flooded while the ship was in a laden condition;
- a gap in the additional safety measures for bulk carriers contained in the International Convention for the Safety of Life at Sea (SOLAS), 1974, Chapter XII, regulation 5 which does not require an assessment to ensure bulk carriers of 150 m or more in length of double-side skin construction, designed to carry solid bulk cargoes with a density of 1,000 kilograms per cubic meter (kg/m3) and above, constructed on or after 1 July 2006 with any part of the longitudinal bulkhead located within B/5 or 11.5 m, whichever is less, inboard from the ship’s side at a right angle to the centerline at the assigned summer load line can withstand the flooding of any one wing tank in all loading and ballast conditions; and
- ineffective assessments of structural damage identified when the ship was in dry dock in 2011, 2012, and 2015 which failed to determine the cause of the structural damage, identify any potential defects with the conversion design, or require the development of appropriate repair plans.
As a converted VLCC, Stellar Daisy carried ore cargoes only in what were the centre tanks of the ship when operated as a tanker. The port and starboard wing tanks being used for ballast purposes. The ship was one of several converted ore carriers most of which were removed from service following the loss of the Stellar Daisy and structural weaknesses being found in similar vessels.
A copy of the report can be found at https://www.register-iri.com/library/