The growth of the offshore wind market is accompanied by larger wind farms, whose electricity needs to be transported to shore.
Offshore converter stations are used for combining and converting the electricity generated from the wind farm for transport to shore.
The increase in the electricity produced by wind farms has led to converter stations growing as well.
This creates an issue, as for many current lifting vessels they are becoming too heavy to lift and place offshore.
Furthermore, new wind farms are currently still being built in shallow water, so vessels should be designed taking this into account if they are to place the converter stations.
As lifting by crane is preferred in the industry, this research looks into the use of semi-submersible crane vessels for lifting converter stations, as these are the largest crane vessel category and have the greatest lifting capacity. \par

Existing semi-submersibles are designed for operating in deep water and thus with little concern for limited water depth.
Consequently, current vessels have large draughts for working in rough seas but are not able to work in the shallows.
The performance of semi-submersibles in shallow water is a little researched topic, both in terms of designing these vessels for this condition as well as operating them at limited draught.
For this reason, this research proposes a new early-stage design model that includes the fundamental limitations for lifting in shallow water and addresses the research question:
\emph{How can the design of semi-submersible crane vessels be improved to lift at least 11,000 tonne substations in shallow waters of less than 30 m in weather conditions with significant wave heights of up to 2.5 meters?}
To answer this research question, the research looks to identify trends of optimized vessel parameters for the design of semi-submersibles for use in shallow water.\par

To find optimized designs for the lifting of converter stations in shallow water, a parametric model will be made within this research, which is then optimized.
This model will make use of the IOC-SAMO-COBRA algorithm to find designs that are optimized for three conflicting objectives.
These objectives are the light weight of the vessel, the water depth that it requires to lift a representative converter station and the operability of this vessel in waves at the required draught.
Applying these objectives, Pareto optimal solutions will be calculated for this situation.
By analysing the results of the model, trends are found for the optimum configuration of the vessel parameters for lifting 11,000 tons converter stations in shallow water.

Offshore construction vessels produce significant greenhouse gas (GHG) emissions, which led to the need to understand how operational decisions can mitigate their environmental impact. This thesis investigates the link between operational decision making and vessel emissions, focussing on Jumbo Maritime’s offshore installation projects. A mixed methods approach was adopted, which combined quantitative analysis of vessel operational data with qualitative insights from stakeholder interviews. Detailed analysis of daily progress reports, energy system models, and fuel consumption records allowed the quantification of emissions for each operational activity. Meanwhile, interviews with on- and offshore managers showed how factors such as contract requirements and project complexity influence decision-making in practice.
The results identify which activities drive the highest emissions and why. Dynamic positioning (DP) during offshore operations and transits emerged as the major contributor to fuel use and emissions, whereas periods at anchor or in port resulted in minimal fuel consumption. Unplanned downtime, especially waiting on weather and technical breakdowns, contributed substantially to emissions.
Crucially, the study found that certain operational strategies can noticeably reduce emissions without compromising project performance. Key recommendations include using anchoring instead of continuous DP whenever conditions allow, and implementing proactive maintenance programmes to minimise breakdowns and associated downtime. In addition, it is recommended to align contractual terms and planning processes with emission reduction goals to empower crews to choose more sustainable operating modes. By linking day-to-day operational choices with their emission outcomes, this research provides practical guidelines for offshore vessel operators to reduce their carbon footprint while maintaining efficiency and safety.