Submerged Swivel & Yoke (SSY)
The Submerged Swivel & Yoke (SSY) — a cost-effective FPSO mooring system for shallow-to-moderate water depths, integrating yoke, swivel and PLEM on a seabed foundation.
Submerged Swivel & Yoke (SSY)
The Submerged Swivel & Yoke (SSY) is a cost-effective mooring solution for FPSO vessels operating in relatively shallow to moderate water depths of 20 to 50 metres. Built from proven components and designed for long-term unattended service, every critical part is engineered for lifetime use with access for inspection and maintenance.
The SSY base is anchored to the seabed and integrates the Pipeline End Manifold (PLEM) with a mooring yoke that connects by chain to the FPSO's bow. Compared with a traditional jacket soft-yoke system, Lintech's design reduces bending moments on the structure — making it more cost-efficient and less prone to fatigue. Yoke strength and allowable stresses are confirmed by finite element analysis.
Because the SSY can be installed offshore before the FPSO arrives, offshore and shipyard work can be decoupled and scheduled independently; the vessel then hooks up with the assistance of tugs, without needing a dedicated construction vessel.
Capabilities & features
The SSY brings together mooring, fluid transfer and structural support in one submerged system:
- Swivel mechanism for fluid transfer — a swivel stack enabling continuous oil, gas or LNG transfer while the vessel weathervanes freely, without twisting the pipeline connections
- Yoke-based mooring for stability — a rigid yet flexible link, sized to vessel and environmental conditions
- PLEM integration — direct oil / gas transfer without a jetty or additional infrastructure
- Foundation & installation — pile foundations or suction anchors for 20–50 m water depths
- Disconnection capability — quick-disconnect options for cyclone or hurricane-prone fields
Typical applications
- FPSO / FSRU developments
- Shallow-to-moderate water fields
- Marginal & fast-track fields
- Offshore oil, gas & LNG
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