Engineering every step from the quayside to final installation offshore
Moving and installing large structures at sea is among the highest-risk phases of any offshore project. A jacket, topside, monopile, substation or module may spend only days in transit, but the loads it sees during load-out, sea transport and lifting can govern its design, and the cost of a delay or incident is measured in vessel spread days. BH&C Dynamics® provides the naval architecture and structural engineering that supports clients in planning and executing marine operations safely, efficiently and to the satisfaction of the Marine Warranty Surveyor (MWS).

We combine hydrodynamic and vessel analysis with in-depth structural engineering, so the motions, loads and structural checks for the vessel, the cargo and the temporary works are developed consistently, by one team.

LOAD-OUT

• Load-out by skidding, self-propelled modular transporters (SPMT), trailers or lifting
• Tidal and ballast analysis, with step-by-step ballast plans to maintain barge level and trim throughout the operation
• Quay, link-beam and ramp checks; skid-beam and support structure design
• Structural analysis of the cargo during load-out, including support settlement and differential deflection between quay and barge
• Barge mooring at the quay during load-out

SEA TRANSPORTATION AND TOWING

• Transport route assessment and design environmental criteria, including weather-restricted and unrestricted operations
• Vessel motion analysis (RAOs and short- and long-term response) for barges, heavy-lift vessels and semi-submersible transport vessels
• Inertial and wind loads on the cargo; cargo structural integrity during transport, including transport fatigue for long voyages
• Towing analysis: tow resistance, bollard pull requirements and towing arrangement design
• Deck layout and stowage planning

GRILLAGE AND SEA-FASTENING DESIGN

• Analysis and design of grillages, sea-fastenings, stoppers and cribbing
• Load-path checks from cargo through grillage into the vessel’s frames and bulkheads
• Fabrication drawings and material take-off for the temporary works
• Sea-fastening cutting sequences for offshore release

VESSEL AND BARGE STRENGTH ASSESSMENT

• Local deck strength checks for cargo, grillage, crawler crane and SPMT loads
• Global longitudinal strength: still-water and wave-induced shear forces and bending moments
• Finite element analysis of barge and vessel structures where simplified checks are not sufficient
• Strengthening design where required

VESSEL STABILITY AND MOTION ANALYSIS

• Intact and damage stability for transport, lifting and installation conditions
• Hydrostatics, loading conditions and ballast planning
• Frequency- and time-domain motion analysis; operability and downtime assessment

LIFTING ANALYSIS – SINGLE AND MULTIPLE BODIES

• Static and dynamic lift analysis, including dynamic amplification factors (DAF) and skew load factors (SKL)
• Coupled multi-body analysis of crane vessel, cargo barge and lifted object, including tandem and dual-crane lifts
• Lifts in air, through the splash zone and through the water column for subsea structures
• Upending of jackets, monopiles and piles; jacket launch and self-upending analysis
• Rigging design: slings, grommets, shackles and spreader bars or frames
• Design and verification of padeyes, trunnions and other lifting points
• Clearance, crane capacity and lift-path studies

MOORING ANALYSIS

• Spread mooring analysis for barges, crane vessels and accommodation vessels, at the quay and at the offshore site
• Quasi-static and dynamic mooring analysis in intact and damaged (line-failure) conditions
• Anchor and mooring line design, and anchor holding capacity
• Mooring pattern layout near existing platforms, pipelines and subsea assets
• Dynamic positioning (DP) capability assessment

FLOATOVER INSTALLATION ENGINEERING

• Floatover feasibility, concept development and vessel selection
• Docking analysis: vessel entry into the jacket slot, fender and docking-system loads
• Mating analysis: load transfer from vessel to substructure, ballasting and tide strategy, and impact loads on leg mating units (LMU) and deck support units (DSU)
• Coupled vessel–topside–jacket analysis, and vessel separation and exit
• Design of floatover hardware – LMUs, DSUs, sway and fender systems – which we can also supply

JACK-UP AND OFFSHORE INSTALLATION SUPPORT

• Site-specific assessment of jack-up units, including leg penetration, punch-through risk and preload
• Offshore wind installation engineering: monopile and transition piece handling, upending and installation; jacket and offshore substation installation
• Pile handling, stabbing and driving support

OPERATION PLANNING AND DOCUMENTATION

• Weather-window analysis and operational criteria, including planned-operation durations and α-factors
• Marine operation procedures, method statements and step-by-step ballast and operation sequences
• HAZID and HAZOP participation and contingency planning
• Document packages prepared for MWS review and approval, and close-out of MWS comments
• Offshore and quayside engineering support during execution

DECOMMISSIONING

• Engineering for topside and jacket removal: lift analysis, cutting sequences, sea transport and reverse load-out

Typical Deliverables

• Marine operation design basis and environmental criteria
• Analysis and design reports for load-out, transport, lifting, mooring and floatover
• Grillage, sea-fastening and rigging drawings
• Ballast plans, stability booklets and operation procedures
• MWS submission packages and comment close-out

Structure and vessel together – our structural integrity background means cargo, grillage, sea-fastening and vessel strength are checked as one load path, not by separate teams.

MWS-ready deliverables – calculations and procedures are prepared to the format and level of detail marine warranty surveyors expect, which shortens approval cycles.

Engineering through to hardware – from float-over analysis to the supply of LMUs, DSUs, fenders and boat-landing hardware.
On site when it matters – our engineers support load-out and offshore execution, so issues are solved in real time.