BACKGROUND: The more complex and perilous a sociotechnical system is, the more crucial it is to have users and other relevant stakeholder groups in focus throughout its design lifecycle. In the design and development of ships and ship systems, there has been resistance towards the integration of ergonomic principles through a human-centred approach as well as to involving the user. This inattention can result in an inadequate design, which may have negative repercussions on usability, ultimately threatening the safety of onboard operations, overall system performance and the well-being of the crew. OBJECTIVE: This study explores the perceived success factors of participatory ergonomics based on the standpoint of young seafarers. METHODS: Such is achieved by examining a focus group with cadets inspired by Grounded Theory approach. RESULTS: The findings reveal user participation as a designer’s essential contact with reality, provided that a set of preconditions that supports the success of participatory ergonomics can be fulfilled: involving the right users and filling in the gap between end-user needs and ship-owner requirements. The consequent success factors are described at a usability level, an intrinsic level for the end-users, and ultimately at the level of increased safety and efficiency. CONCLUSIONS: User input may not only affect design as an outcome, it may also influence the way participatory ergonomics is performed in the maritime sector.