Highlights • Ship environmental initiatives lack public transparency regarding assessment methods and results. • Many are limited in environmental scope and applicability to a wide range of vessels. • Low performance requirement thresholds indicate limited certification ambition. • Assessment of vessel performance based on design rather than operational performance.

Abstract Pollution from ships is a significant environmental concern. Maritime environmental legislation has tightened in recent years since the introduction of the MARPOL 73/78 regulations, however there is often a significant time gap between when the regulations are adopted and when they legally enter force. The emergence of private voluntary environmental initiatives has occurred in an attempt to bridge this gap, reduce environmental impacts, and raise the environmental profile of ships. However, there are inconsistencies in the methodologies used to define ship performance, and the number and diversity of initiatives available for use can cause confusion, hindering progress towards greater sustainability. A critical analysis of existing environmental initiatives in the shipping industry has been conducted, challenging the applicability, scope, and environmental ambition of the methodologies adopted. The analysis highlights significant limitations of initiatives with regards to transparency, assessment rationale and environmental scope, and flexibility to be ship specific. Many show bias towards certain environmental indicators, while others have limited ambition. This paper challenges the effectiveness of existing environmental initiatives used in the shipping sector to promote environmental improvements beyond current regulatory requirements, and proposes an objective, quantifiable approach to assessing vessel environmental performance.