Advancements in Float-over Technology: A Technical Review of Leg Mating Units (LMU) and Deck Support Units (DSU)

The installation of large integrated offshore topsides has increasingly relied on the float-over method, particularly for structures exceeding 20,000–50,000 MT where heavy-lift vessels are either cost-prohibitive or operationally constrained. Despite the widespread adoption of float-over technology, the engineering literature remains fragmented regarding the mechanical behavior, performance limits, and selection criteria of Leg Mating Units (LMUs) and Deck Support Units (DSUs)—the critical interface hardware enabling safe and controlled topside mating. This review consolidates vendor specifications, peer-reviewed research, and industry guidelines to present a unified technical reference for elastomeric and hydraulic LMU/DSU systems.Key contributions of this paper include:(1) an integrated comparison of elastomeric versus hydraulic systems with quantitative stiffness, load-capacity, and friction-performance ranges; (2) a structured review methodology modelled on engineering evidence-mapping practices; (3) a risk-adjusted Value Engineering (VE) framework incorporating cost-benefit drivers, motion-compensation needs, and environmental constraints; and (4) the introduction of a practical risk matrix to guide LMU/DSU selection under project-specific uncertainty.Findings confirm that elastomeric systems offer reliable, cost-effective performance in moderate environments, while hydraulic systems provide superior control and extended weather windows for high-risk installations. This consolidated framework supports design optimization, procurement decisions, and risk-based hardware selection in future float-over projects.