3,500-Ton Semi-Submersible Floating Wind Foundation SPMT Loadout Manual
Marine warranty surveying and heavy transport manual for rolling 3,500T to 5,000T steel floating substructures from quay fabrication yards onto semi-submersible barges: synchronized multi-file SPMTs, high-rate ballast dewatering, and grillage sea-fastening.
1. Multi-File SPMT Hydraulic Equalization & Column Support
Next-generation 15MW to 20MW offshore floating wind platforms (such as triangular semi-submersible designs featuring three 14m-diameter buoyant steel columns linked by horizontal pontoons and cross-bracing) weigh between 3,500 and 5,000 metric tons. Handling these massive structures across a shipyard quay requires 112 to 144 axle lines of Self-Propelled Modular Transporters (SPMTs) linked electronically via multi-file CAN-bus telemetry.
Separated into three independent hydraulic suspension groups positioned under each of the three buoyant column node clusters to maintain uniform tire contact pressure.
Interposed between steel transport grillage and hull bottom plating to distribute localized point stresses under 30 MPa.
The SPMT travel speed during quay transit is restricted to 3.0 meters per minute (0.18 km/h) to maintain complete directional control and minimize dynamic inertia forces during movement across the quay threshold.
2. Tidal Window Matching & High-Speed Ballast Water Compensation
The critical hazard phase occurs when the leading SPMT wheel lines transition across the RoRo linkspan ramps from the rigid concrete quay onto the floating barge deck. As the 3,500T weight transfers onto the vessel, the barge displaces downwards while the tidal curve continuously raises or lowers the sea water level:
Ballasting System Architecture
The transport barge utilizes internal ballast tanks fed by high-rate submersible dewatering pumps capable of shifting over 12,000 m³/hr of seawater. Pumping rates are actively adjusted based on laser elevation sensors monitoring the quayside-to-barge ramp linkspan hinge angle.
Tidal Window Coordination
Loadout operations are scheduled during slack water intervals (neap tide window preferred with tidal variance < 0.5m/hr). The entire load transfer across the quay must complete within a pre-calculated 45-minute operational envelope.
Barge Mooring Winch Auto-Tensioning
Four 80-ton constant tension hydraulic winches secure the barge bow against the quayside pneumatic Yokohama fenders, preventing horizontal gap opening greater than 25mm during vehicle transit.
3. DNV-ST-N001 Marine Warranty Survey (MWS) & Sea-Fastening
Once positioned centrally on the transport barge deck, the SPMTs hydraulically lower the substructure onto permanent steel grillage towers. Sea-fastening welding proceeds in accordance with DNV-ST-N001 standards:
- • Shear Lug Keyways: Heavy fabricated steel shear keys welded to the barge deck engage internal column recesses to resist dynamic horizontal wave acceleration up to 0.45G during ocean tow.
- • Tubular Diagonal Sea-Fastening Struts: 24-inch diameter API 5L X65 structural steel tubular struts welded between barge hard points and substructure node joints.
- • 100% NDT Weld Inspection: Phased array ultrasonic testing (PAUT) and magnetic particle inspection (MPI) on all load-bearing sea-fastening weld seams prior to MWS certificate of approval issuance.
Floating Wind Foundation Architectures
Request Floating Wind Loadout Study
Connect with Exspeedite's marine transportation group for tidal simulation, barge ballast sequencing, and DNV MWS approval packages.