The Problem
A demanding tidal environment
The client needed a full offshore substation inspection covering two offshore substation platforms (OSPs) at an operational wind farm off the North Wales coast, and wanted clean, comparable data across both structures without committing to a larger containerised spread or putting divers in the water.
The campaign covered every jacket face, leg and node on both structures, along with cable risers, J-tubes, anode condition, marine growth, welded connections and full cathodic protection (CP) profiles down each leg. All work was completed without divers in the water.
Strong tidal currents around the site meant the team had to plan each dive around slack water windows. The vessel tied off on the appropriate boat landing for each face of the structure, holding position against the tide while the ROV worked methodically around the jacket. On stronger tides the ROV was recovered until conditions eased; on better days the team completed full faces, legs and cable risers in a single dive.
That kind of tide-driven cycle is only sustainable when the planning, the kit and the crew are all aligned. Knowing when to launch, when to recover and how long the productive window will last is a skill built up over years of working offshore.
The Campaign
Nine days, mobilisation to demobilisation
Built up in a day
Equipment was hand-carried onto the pier at a local port and transferred to the CTV. By the end of day one the topside was built, satellite connectivity was live for real-time data transfer, the CP equipment had been function-tested and the ROV had completed a wet test alongside.
A tide-driven cycle
Each day the vessel transited to one of the OSPs, tied off on the boat landing that suited the current direction and timed the launch around slack water. The ROV stayed in through the working window while the vessel held position against the tide and the team worked face by face around the jacket.
Visibility every day
Every working day closed with a Daily Progress Report: hours, scope, percent complete, anomalies and CP data. The client could see progress as it happened, and the final report was built directly from that daily record.
Our Solution
The right system for the job
The Ocean Modules V8 M500 is a compact, all-electric, observation-class ROV with vectored thrust, full HD imaging and a 500 m depth rating. It mobilises in hours rather than days, deploys from a standard CTV deck, and is small enough to work in close to jacket legs, risers and J-tubes where larger systems struggle for access.
For OSP inspection campaigns, that combination matters. It removes the need for a larger containerised spread, reduces vessel costs and gives the team the manoeuvrability needed to capture clean inspection data on complex steelwork.
The Scope
What the ROV inspected on each platform
General visual inspection
Every jacket face: horizontals, horizontal diagonals, K-nodes, central nodes, vertical members and vertical diagonal members at the specified inspection elevations.
Export cable inspection
Risers, clamps and J-tubes for the export cables, from surface entry down to burial.
Anodes and marine growth
Anode condition and marine growth assessed on every member and node.
Welded connections
Weld checks wherever the connection was visible through marine growth.
Cathodic protection profiles
Full CP profiles down each leg, with readings logged metre by metre through the water column.
Anomaly logging
Any feature needing follow-up recorded with its location, description and supporting imagery.
On site
The Result
Clean data, structured reporting
Each working day produced a complete Daily Progress Report covering hours, scope progress, anomalies and CP data. The client received high-quality video, stills, a structured CP dataset and full anomaly logs in real time throughout the campaign, with the final deliverable building directly from the daily record.
Both platforms were inspected in full within the planned nine-day window, with no divers in the water and no requirement for a larger marine spread.
Delivered to the client
- High-definition video of every jacket face, leg and node
- Stills of anomalies, anodes and welded connections
- Full CP profiles down each leg, logged metre by metre, as a structured dataset ready for year-on-year trend comparison
- Anomaly log with location, description and supporting media for every item
- Daily Progress Reports: hours, scope, anomalies, CP data
- Final report built directly from the daily record
Offshore wind operators are under steady pressure to inspect ageing assets more often, more efficiently and more safely. CTV-based offshore substation inspection by ROV, done by a team with real operational experience, is now a credible, efficient route for major asset inspection campaigns. The right kit, the right planning and the ability to adapt when conditions change can take complex OSP jackets from “weeks of work” to “days on site”.
Why Atlantas Marine
What made the difference
Compact, agile equipment
The V8 M500 mobilises and demobilises in hours, deploys from a standard CTV and works in confined positions around jacket legs and risers where larger systems would struggle.
Operational experience
Planning around tidal windows, tying off and holding position safely against the structure, managing launch and recovery from a CTV in current, and keeping the ROV productive across short slack periods. That comes from running the equipment in real conditions, not just supplying it.
Adaptability
When an unexpected operational issue arose mid-campaign, the team had the kit and the know-how to resolve it offshore with the ROV, avoiding extra vessel intervention and unplanned downtime.
Clean reporting
A complete Daily Progress Report every day gave the client real-time visibility of the campaign and a structured dataset for the final deliverable.
From "weeks of work" to "days on site". Save time. No dive. No risk.
Planning an OSP or wind farm inspection campaign?
Talk to a team that has done this work from a CTV deck, in real tidal conditions, and can mobilise a compact ROV spread in hours.
How can we help?
Tell us about your inspection campaign
Send the ROV operations team a few details about the asset, the location and the timing, and we will come back to you with how we would approach it.