Seakeeping evaluations are important in the early design stages in order to ensure that vessels can sail the seas and execute their missions safely in the intended conditions. Such evaluations require a set of criteria that translate seakeeping design requirements into tangible measures for decision-making. Despite the availability of seakeeping criteria, certain unsuitable considerations and specifications currently in use result in challenges to crew and operations that do not become apparent until later in a vessel’s service. Though not claimed to be exhaustive, this paper catalogues and reviews the seakeeping criteria commonly used to date, guided by findings from focus group discussions and semi-structured interviews.  The paper unearths the original sources whilst discussing the scientific basis for these criteria and standards. Particular attention is given to the early design stages and opportunities for improvement and further development are highlighted. Findings from this study indicate that it is necessary to develop seakeeping criteria for certain vessel types and that there are opportunities to improve seakeeping criteria addressing crew well-being, performance and safety.

Determining the operability of a vessel is a critical task for the naval architect since it provides valuable information for vessel owners and operators on the vessel’s performance. This task requires a seakeeping analysis and a set of seakeeping criteria to evaluate predicted vessel motions. These seakeeping criteria link the performance and safety of the crew and vessel to operability. Existing seakeeping criteria (e.g., NORDFORSK, NATO STANAG 4154) are specified for certain vessel types and not applicable to different tasks and operational activities aboard work vessels such as pilot boats, ocean research vessels, dredgers, pipe laying crane vessels. Being relatively small in size, these work vessels are susceptible to the perils of waves, yielding motion responses that can degrade crew performance. This paper proposes a framework for specifying seakeeping criteria for efficient task performance, focusing primarily on the effects of motions on the crew and system performance. Findings from preliminary interviews with some crew at the Swedish Maritime Administration and the Swedish Sea Rescue Society align with the literature on the effects of motions on crew performance, including motion-induced interruptions, motion-induced fatigue, motion sickness, and effects on motor skills and perception. These findings from the interviews are used in a case study to demonstrate the approach of the proposed framework. The proposed framework refines further and adds to the established structure of the traditional seakeeping assessment since it captures, in addition, the effect of motions on crew performance.

A challenge during vessel design is translating functional requirements into seakeeping evaluation metrics to ensure that delivered vessels are fit for purpose. This paper presents an approach based on task analysis methods for identifying and decomposing motion-critical tasks from given functional requirements, by which seakeeping evaluation metrics can be derived. The method is applied and guides the reader through deriving seakeeping criteria and standards for two case study vessels, focussing on crew performance. Findings suggest that the seakeeping evaluation metrics of different vessels will differ based on their purpose or mission. It is envisioned that the method will guide the seakeeping evaluation of vessels, which has been less prioritised in vessel design. This method can potentially ensure crew performance and safety in the early design stages.

Motion-induced interruptions (MIIs) represent a critical mechanism through which environmental motion degrades human performance in moving work environments. Although MIIs are widely referenced in maritime operability assessment and human-centred seakeeping analysis, the concept remains fragmented across disciplines, with inconsistent definitions, indicators, and quantification methods. This study presents a systematic literature review aimed at characterising and synthesising the MII concept within engineering and human-performance contexts. A structured search strategy was conducted in Scopus, complemented by reference screening and expert-identified publications, resulting in 44 included studies spanning the period 1980-2024. The review analyses how MIIs are defined, operationalised, quantified, and applied across fields including naval architecture, ergonomics, biomechanics, and human factors. The findings show that MIIs are consistently associated with disruptions of task execution caused by motion-induced instability, typically manifested through balance loss, postural recovery actions, task interruption, or compensatory behaviour. Quantification approaches range from observational event counting and simulator experiments to analytical prediction models based on tipping, sliding, and force-threshold exceedance. The review further identifies a lack of standardised approaches for defining acceptable interruption rates in relation to operational performance and safety. Based on the synthesis, a consolidated definition of MII is proposed, framing MIIs as duty interruptions caused by the physical motion of the environment that force individuals to stop, adjust posture, or change pace during task execution. The study highlights the role of MIIs as a bridge between engineering operability assessment and human performance evaluation and identifies key directions for future standardisation and modelling efforts.

Motion-induced interruptions (MIIs) indicate degraded task performance on marine vessels and serve as a task-based seakeeping evaluation metric. The most widely used MII prediction approaches define the interruption threshold geometrically, from an assumed stance and orientation. Such a threshold marks rigid tip-over, but these interruptions also include a person adjusting posture in response to vessel motions to continue a task. This study develops a task-informed estimator that predicts MII rates at the resolution of individual tasks, derived by systematically reducing Graham’s resultant tipping and sliding conditions. The reduction removes the rotational-inertia terms from the destabilising force and replaces the geometric threshold with a task-defined MII coefficient measured at observed interruptions. The destabilising force is independent of the individual, while the coefficient carries the task-specificity. The estimator was compared against Graham’s resultant tipping condition across three tasks, three sea states, two forward speeds, and a range of headings. Removing the rotational-inertia terms had a minor effect, whereas replacing the threshold had a dominant one, producing consistently higher rates. Under identical vessel motions, the predicted rates differed markedly across the three tasks, indicating that MII prediction is task-dependent. The estimator therefore supports task-based seakeeping evaluation in vessel design and procurement.