© IMechE 2020.This study conducts a practical application of shipboard operation human reliability analysis (SOHRA) to a crankshaft overhauling operation of a general cargo ship at dry-docking period. The SOHRA approach includes error producing condition (EPC) and general task type (GTT) parameters to consistently calculate the human error probability (HEP) values of operation steps. In this case, a comprehensive overhauling of main engine was planned at shipyard since the ship has experienced a catastrophic failure. An onboard survey to ship engine room is conducted to monitor the operational conditions. The targeted operation, involves disassembly, maintenance, and reassembly stages, is monitored based on 39 sub-tasks. According to the initial findings, immediate recovery actions are suggested to eliminate critical safety issues in a timely manner. Moreover, an extended discussion through long-term safety recommendations are also provided. The results revealed from case study illustrates that HEP values in maintenance operations are sensitive to ship operating conditions. The proposed approach is found very useful by company executives to support ship technical superintendents in critical operation monitoring. The further study is considered to develop mobile application of SOHRA specific to maintenance operations onboard ships.