201256 Excess chemical cargo discharged

A chemical tanker was loaded with three parcels for multiple ports. At one of the discharge ports, as per manifest, the vessel was to discharge a major portion of Di-ethyl glycol (DEG) – a total of 2,408 tonnes from two tanks, along with small quantities of the other two cargoes. After discharge, ullages and tank calculations showed that the vessel had inadvertently discharged a quantity of 2,606 tonnes, an excess cargo quantity of 198 tonnes.

Result of investigation
1 In the original discharge plan, the stopping ullages of the DEG cargo tanks were found to be correct, but when recalculating prior to discharge, the C/O had obtained different figures due to a clerical error. Believing the original plan to be incorrect, he amended the ullages in the discharge plan;
2 The C/O did not discuss the discrepancy and revised stopping ullages with the OOW and Master, resulting in a one-man error.

Corrective/preventative actions
1 The management office and the charterer were immediately informed of the error;
2 P&I Club surveyor was urgently summoned to attend;
3 Master and C/O independently re-calculated the cargo quantities for the remaining discharge ports and relayed the figures to the charterer;
4 Shipboard procedures were amended to include the instruction that the Master shall personally verify the C/O’s pre-loading and predischarge cargo calculations, supervise cargo operations at critical stages and that all cargo and tank cleaning plans, and any revisions shall be verified / approved / signed by the Master and OOW;
5 Investigation report shared within the fleet and to form part of preboarding briefing for all senior officers;
6 Future crew changes to allow for sufficient overlap of deck officers when vessel is scheduled to call at multiple load or discharge ports;