WP 3: Vessel motion and vibrations. Vessel and engine / Crew safety and work environment
WP leaders Lisa Froholdt (Centre of Maritime Health and Society, CMSS), Marie Lützen (Institute of Mechanical and Electrical Engineering), and Co-leader: Luis David Avendaño-Valencia (Institute of Mechanical and Electrical Engineering)
WP 3 is carried out in collaboration between the faculties for Health and Engineering. Vessels operating in the offshore sector are heavily exposed – they operate in waters with strong winds and big waves. When making room for crews to disembark and enter the turbine, ship operations close to wind turbines or offshore constructions require fast maneuvers with varied speed as well as frequent starts and stops.
The work is concentrated on the identification of consequences of motion and vibration for both vessel and crew. The heavy usage will rapidly wear out the equipment on board and, in some cases, also cause and accelerate damages. The physical and psychological stressors involved in working onboard these vessels will be identified and possible solutions to minimizing the impact of the stressors on the crews’ work environment.
PhD studerende Casper Aaskov Drangsfeldt, Institute of Mechanical and Electrical Engineering, (February 2023 - )
In the rapidly expanding offshore wind energy market, Operation and Maintenance (O&M) for Offshore Wind Turbines (OWTs) presents significant challenges. Costs associated with O&M for OWTs are substantial, particularly due to restricted accessibility and the need to charter specialized vessels, such as Crew Transfer Vessels (CTVs), for personnel transportation. In addition, CTV operations are often cancelled due to harsh weather, creating a critical need for continuous operation during favourable conditions. This demand frequently leads to corrective maintenance of the CTV, which increases the risk of unexpected breakdowns. Maintaining CTVs in optimal condition becomes crucial to ensure reliability and uninterrupted operation. Thus, an optimal maintenance strategy, particularly a condition-based approach, is imperative, which can be facilitated by the technology of Structural Health Monitoring (SHM).
The concept of SHM involves continuously collecting and analyzing data related to the condition of a given structure to identify deviations from a normal, undamaged condition. When changes or anomalies are identified, such as unusual vibration levels, these could indicate potential damage, providing a damage diagnosis before reaching a critical level. However, changing operational and environmental conditions can alter the definition of what constitutes a normal, undamaged condition, complicating the process of detecting deviations caused by damages. In the context of CTVs, the operational conditions are shaped by numerous variable factors such as human decisions and complex interactions between operations and the environment, making it highly challenging to define a consistent normal condition as this definition varies with operational conditions. In addition, highly variable environmental conditions at sea further complicate the process. This is crucial to address for robust SHM.
The primary focus of this Ph.D. is to develop a robust vibration-based SHM maintenance strategy for structures subjected to time-variant operating conditions, specifically focusing on the propulsion units of a CTV. Through robust SHM, damage diagnosis is enabled, allowing the crew onboard to accurately assess whether to continue operating as normal, operate with reduced power, take alternative routes or even return to port. Additionally, it is expected that potential causes of accelerated deterioration can be identified by tracking when damages are recorded. Overall, robust SHM provides a more nuanced approach to CTV operation, increasing the reliability of CTVs.
Motion Sickness Among Offshore Wind Farm Workers
PhD Student Andrew Fenn, Centre of Maritime Health and Society, CMSS, (Marts 2023 - )
The project aims to identify the prevalence of motion sickness symptoms among offshore wind farm workers travelling to and from wind farms aboard crew transfer vessels. The study also aims to investigate barriers to, and enablers of reporting among windfarm workers, looking at the health and safety implications of seasickness and the broader sociological dimensions impacting their experiences and reporting behaviours.
Improving the comfort of crew and passengers on board ships
PhD student Elma Ramic, Institute of Mechanical and Electrical Engineering, (Marts 2024 - )
Background: Today, the sail or not-sail decision for crew transfer vessels (CTVs) is based either on fixed parameters associated with environmental conditions or on rules-of-thumb. These decision constraints aim to ensure the safety of operations, both during transfers and maintenance of turbines. However, amongst these considerations, one critical and equally important factor remains overlooked: the risk of motion sickness experienced by crew and technicians on board crew transfer vessels. In addition to discomfort, seasickness can affect both cognitive and physical performance, potentially leading to hazardous events for the technicians during operations. Currently, no models are available to predict seasickness for this specific purpose as existing work primarily focuses on the operational criterion Motion Sickness Incidence (MSI) as a quantitative measure of sickness. The derived formulation of the MSI index is based only on vertical accelerations and emesis as a seasickness indicator. Furthermore, existing research on the topic is based on larger vessels, such as ferries and warships, whose structural and dynamic behavior are strongly dissimilar to those of CTV.
Objectives and methodology: The project aims to develop a machine learning tool capable of estimating and predicting the probability of seasickness based on given weather forecasts and sea conditions. In addition to supporting the sail-or-not decision-making, the tool will propose alternative sailing, with a focus on minimizing the risk of seasickness. To ensure that the suggested solutions do not impose an environmental burden, energy efficiency analyses will be conducted. The development of the tool re-quires multi-factorial analyses where technical factors are combined with human and psychological factors. Thus, the basis of the tool heavily relies on interdisciplinary collaboration across multiple scientific fields. The human and psychological aspect is the scope of a separate project and will thus be managed by researchers from the Faculty of Health Sciences. Currently, a substantial amount of motion data is being logged onboard the MHO Grimsby, which is owned and operated by MHO Co A/S. Additionally, a seasickness display, detailing various symptoms and their corresponding intensities, has been installed.