Floating wind turbines face their greatest structural threat not from the tallest waves, but from waves arriving at an angle
Picture a floating wind turbine the size of a city block — 120 meters wide, riding ocean swells with its hull anchored 30 meters below the surface. Structures like the Moray Base platform are engineered to survive some of the harshest conditions at sea, and conventional wisdom holds that bigger waves mean bigger danger.
A new computational study challenges that assumption. Researchers modeled how different wave conditions stress the Moray Base structure and found that one variable — largely overlooked in standard design thinking — may matter more than wave height or current speed combined. The culprit has less to do with raw ocean energy than with the platform’s own shape.
A new kind of offshore wind platform
The Moray Base is a 15-megawatt semi-submersible floating wind turbine designed by Dutch marine engineering firm Maridea BV. Its footprint stretches 120 meters wide, its blades span 110 meters, and its hull sits 30 meters below the waterline. This isn’t a nearshore installation bolted to the seafloor — it’s a platform built to operate where the ocean floor drops too deep for fixed foundations.
UHPC offers real advantages in corrosion resistance and durability, but material choice alone can’t compensate for inadequate attention to directional loading.
That distinction matters. Deeper water generally means stronger, more consistent winds, and as countries push offshore wind capacity further from shore, floating platforms become the only viable option. China, which has set carbon-neutrality targets and is actively scaling offshore wind, provides much of the policy urgency driving research like this.
The Moray Base consists of floating foundation columns, heave plates that dampen vertical motion, cross-bracing connections linking the platform’s long floats, and a semi-tensioned mooring system using six cables. Those connection points — where the bracing meets the floats — turn out to be critical.
Building a virtual ocean — and a miniature one
To study how waves stress the platform, researchers used two complementary approaches. The first was a computational fluid dynamics numerical tank simulating fifth-order Stokes waves — a virtual tank measuring 1,000 meters long, 360 meters wide, and 490 meters deep.
The second was a physical scale model built at a 1:68.5 ratio and tested at Jiangsu University of Science and Technology. Pressure errors between the two methods stayed below 10%, and wave period errors remained under 2%. For structural analysis, the team chose ultra-high performance concrete (UHPC) modeled in finite element software ABAQUS, with mesh convergence tests settling on a 0.6-meter global mesh size.
Wave height and period: the expected suspects
Wave height behaves roughly as expected. As waves grew from 8 to 11 meters, maximum equivalent structural stress climbed from about 39 MPa to 42.5 MPa — taller waves drive greater heave, which increases hydrodynamic force on the 75-meter submerged floating body.
Wave period tells a more counterintuitive story. Longer periods actually reduce peak slamming pressure. At an 8-second period, maximum pressure at one monitoring point reached about 80 kPa; by 11 seconds, that dropped to roughly 52 kPa. The explanation: slamming pressure is driven primarily by horizontal wave force. As wave period increases, horizontal force weakens — pulling peak pressure down even as the platform bobs more dramatically up and down.
Current flow: a hidden amplifier
Adding current velocity produced a notable result. At one monitoring point, slamming pressure jumped 66% between zero current and 6 meters per second — a far larger swing than wave height alone produces. When current flows against the platform, water piles up on the windward side, raising local pressure independent of the wave itself.
Structural stress responded more modestly, rising only about 5% across the tested range. That divergence matters because pressure and stress don’t scale together under current loading. Wave-only models may significantly underestimate forces whenever tidal or ocean currents are present.
The angle problem: why geometry is the real danger
Waves arriving at 45° and 90° to the platform’s long axis generated structural stress far higher than head-on (0°) waves — and the reason is geometry. When waves arrive at 0°, the long floating body aligns with their direction of travel, limiting stress concentrations. At oblique angles, that coordination breaks down. Cross-bracing connections are suddenly exposed to combined bending and torsional forces, while the mooring system loses the symmetry that normally lets the platform follow wave motion.
The connection points between the platform’s long floats are the critical weak spots. Any platform operating where oblique wave directions are common must reinforce those junctions specifically.
What this means for the next generation of offshore wind
The study establishes a clear hierarchy of risk: wave direction angle poses the greatest structural threat, followed by flow-induced liquid accumulation, then wave height, then wave period. That ordering runs counter to how many designers intuitively prioritize loading conditions.
UHPC offers real advantages in corrosion resistance and durability, but material choice alone can’t compensate for inadequate attention to directional loading. As platforms move into deeper, more exposed waters, oblique sea states aren’t edge cases — they’re routine. Future research must examine irregular real-world waves and combined wind-wave-current loading before these platforms can be validated at commercial scale.
You can learn more about this discovery here: Ye C, Huo F, Yang J, Luo P and Niu J (2026) Research on hydrodynamic characteristics and structural safety evaluation of floating wind turbine based on Moray base. Front. Mar. Sci. 13:1856275. doi: 10.3389/fmars.2026.1856275
Carlos is an engineer with strong expertise in technical and industrial topics. He previously worked at international companies such as Siemens and is multilingual.
