Sunghun Hong

Floating offshore wind is central to Korea's deep-water strategy, but installation choices remain poorly structured at the project-planning level. This paper proposes an installation compatibility framework that organises the selection problem along foundation type, water depth zone, and metocean severity. For each axis combination, the framework returns a feasibility verdict, an operability band, a method-maturity level, and dominant constraint codes. Applied to the Korean East Sea using GEBCO 2026 bathymetry, Korean ERA5 and hindcast data, and four installation methods (fully assembled wet tow, TLP integrated tow-and-tensioning, heavy-lift-vessel-based offshore turbine mating, and catamaran-based onsite installation), the framework yields a foundation-depth-severity compatibility matrix and maps the Ulsan floating project portfolio into it. The matrix shows that the practical installation choice space in Korea is much narrower than the conceptual design space: semi-submersible and barge wet tow form the only rows with Feasible verdicts and Proven maturity across their applicable depth ranges, while spar and TLP concepts remain structurally or logistically gated. The framework complements existing installation reviews and planning models as an installation-compatibility layer upstream of technoeconomic analysis, providing a structured basis for identifying hull-form, port, fleet, and validation investments needed to move currently Conditional foundation-method combinations into Feasible territory.

Bottom-fixed offshore wind turbine installation depends on a limited fleet of wind turbine installation vessels (WTIVs), whose requirements tighten as turbines scale beyond the 15 MW class. With this fleet projected to fall short of demand, concepts that add capacity without competing for the same vessels are of interest. This paper extends the response-based operating envelope of a side-mating dynamically positioned catamaran to four markets: Dogger Bank, Atlantic Shores, the Taiwan Strait, and Korea Sinan. For each market, a 25-year ERA5 hindcast is combined with persistence probabilities from time-domain simulation to obtain scatter-weighted operable fractions, compared against a conventional crane-vessel campaign from published sub-operation envelopes. A per-turbine installation-time metric separates the advantage into time on station and weather operability. The catamaran is the more weather-operable concept at every market; the conventional campaign needs 2.1 to 3.6 times the catamaran's installation time per turbine. The saving combines a site-invariant on-station reduction with a weather-operability gain that grows with site exposure, becoming dominant at the Atlantic markets. Korea Sinan shows the smallest advantage as calmer seas narrow the gap. At the Taiwan Strait, a full catamaran campaign fits one non-typhoon season; the equivalent conventional campaign spans about three.

Jack-up vessel supply constraints motivate alternative installation approaches. A catamaran-based onsite concept, in which a pre-assembled turbine is mated directly to the pre-installed monopile, has been validated for floating spar foundations but not assessed for fixed-bottom monopile-supported turbines. This paper presents the first response-based operability characterisation of the catamaran onsite concept for fixed-bottom turbines, using time-domain simulations of the DTU 10 MW reference turbine over 220 sea-state–heading conditions; allowable horizontal displacement e*_xy and execution time T_h are treated as free parameters. Horizontal displacement is the single active constraint; the vertical limit is non-binding for Hs ≤ 2 m. At the baseline (e*_xy, T_h) = (1.5 m, 70 s), 90.2% of 132 installation-heading conditions satisfy the persistence criterion; peak and persistence criteria cross near T_h ≈ 290 s. The 75% operability contour extends to T_h = 150 s and the 50% contour to T_h = 600 s and e*_min ≈ 0.5 m. The scatter-weighted annual operable fraction at Sørlige Nordsjø II is F_SN2 = 92.8%, within 0.5 pp of the maximum accessible fraction; operability is limited by the metocean distribution rather than catamaran response.

The installation of the present wind farms Hywind Scotland and Hywind Tampen are both carried out by towing the fully assembled wind turbine from the assembly site in the Norwegian fjords to the final offshore site. In the present study an alternative installation method is proposed where the fully assembled tower is transported to the site on the installation vessel and mounted onto the preinstalled floating substructure (a spar buoy). The paper presents a brief outline of the design process for the proposed concept and gives an overview of the work done to evaluate variations of the installation vessel and the proposed lifting mechanism. The paper is a summary of the results obtained by a project team in SFI MOVE addressing marine operations related to installation of floating offshore wind turbines.