Regional operability and per-turbine installation time for bottom-fixed offshore wind: Side-mating catamaran versus conventional crane vessel across four markets

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.