Cable Installation Analysis

We perform detailed cable lay analysis covering catenary behaviour, mechanical loading, and touch-down point assessment throughout the installation process. Our analysis accounts for vessel motions, current loading, seabed topology, and cable mechanical properties to verify that installation loads remain within manufacturer limits. We model tension profiles under varying environmental conditions, analysing a range of lay tensions for each water depth to determine minimum and maximum operational limits.

We also analyse supplementary operations including survival lay, cable initiation, laydown and recovery. Survival lay analysis assesses cable behaviour in higher sea states across head and stern sea conditions to determine survival limits and inform operational decision-making when weather windows close. Cable initiation analysis covers the controlled deployment of cable from the vessel to the seabed at the start of each lay section, assessing tensions and bend radii. Laydown and recovery analysis determines safe procedures for lowering the cable end to the seabed or recovering it, accounting for water depth, current loading, and vessel positioning to ensure cable integrity is maintained during these critical operations.

We analyse 1st and 2nd end cable pull-in operations at offshore substation platforms, jacket structures, and monopile foundations. Our analysis covers pull-in tensions, cable bend radii through J-tubes and I-tubes, hang-off loads, and mechanical loading on the cable during approach and entry. We account for vessel motions, current loading, and platform interaction to verify that cable limits are maintained throughout the pull-in sequence.

We perform shore pull-in analysis covering the cable approach to landfall and transition through the HDD duct or open-cut trench. Our analysis determines winch pull tensions and cable mechanical loading to ensure safe installation through the nearshore and beach section. Supplementary analyses include float/buoyancy spacing optimisation, worst-case single failure of flotation/buoyancy and controlled lowering activities.

We analyse cable recovery operations covering hook-in and recovery to deck, assessing tensions, bend radii, and mechanical loading as the cable is brought back on board the vessel. Our analysis accounts for vessel motions and environmental conditions to determine safe operational limits for recovery.

We perform cable jointing analysis for both normal and survival conditions, including fixed heading and limited heading scenarios. Our analysis verifies that cable mechanical limits are maintained throughout the jointing window while the vessel holds position. For joint deployment, we analyse inline joint deployment and omega joint deployment operations, determining safe lowering speeds, tensions, and seabed placement procedures to ensure joint integrity.

We perform cable fatigue analysis for both in-place design and installation conditions using FlexDeck™. In-place fatigue assessments cover the cable's operational life, accounting for wave and current-induced loading, vortex-induced vibration, and seabed interaction at freespans. We also assess fatigue accumulation during long static positions such as jointing operations, where the cable remains suspended from the vessel for extended periods and is subject to continuous vessel motion and environmental loading.

We analyse metocean data against vessel and equipment operational limits (determined from the other analyses listed here) to determine realistic weather windows for each phase of the cable installation. This combined with our offshore experience means you get the most workability for your operations without undue conservatism. Our workability assessments combine vessel motion response with operation-specific criteria to support scheduling and cost estimation, and through FlexDeck™ we provide Weather Downtime Analysis to help understand probabilities.