This study proposes an expert system to aid shipboard personnel for solving ship auxiliary machinery troubleshootings. The developed expert system, called as SHIPAMT(SOLVER), is structured based on PROLOG programming language. Principally, the SHIPAMT(SOLVER) suggests an optimum action code for the shipboard personnel with respect to the established rules on technical knowledge, system indicators, and previous failure experiences from the auxiliary machinery systems. As an illustrative case application, the SHIPAMT(SOLVER) is performed over a probable failure scenario in a ship refrigeration system. Utilization of the SHIPAMT(SOLVER) on board merchant ships ensures an effective decision aid on corrective actions while reducing the response time to failures especially in manoeuvring positions and voyages in critical waters. (C) 2008 Elsevier Ltd. All rights reserved.