Hull cofferdam

The Operation

The Viewport3 team worked with a major North Sea marine contractor to enable accurate fitting of ‘cofferdams’ to the hull of a semi-submersible asset in the Northern North Sea. With the customer seeking a 3d scanning solution, we were contracted to carry out the specification and operation of the capture system, as well as the 3D reconstruction and engineering analysis.

The Challenge

The customer needed a detailed understanding of the shape of the hull, sea chests and appurtenances. Conventional measurement methods would not be able to provide the level of accuracy required, and tend to involve elongated diver campaigns. Inaccurate and imprecise data would add time to the installation process as there would be a greater need for more on-site fitting adjustments.

Moreover, the traditional methods would take longer to mobilise, and indeed to collect the required data. With a quicker scanning operation and accelerated installation campaign, the customer was able to save time, and therefore money.

The campaign posed a number of potential challenges, all of which were identified by Viewport3 and mitigated during the initial discussions. ROV flight paths, camera payloads and lighting augmentations were detailed upfront with the customer’s engineering team, and any likely delays negated prior to mobilisation wherever possible.

The Solution

The Viewport3 method deployed during the scanning activity enabled our client to work an ROV-only campaign, helping to speed up data collection and improve safety outcomes. We designed a project-specific camera and lighting arrangement for the ROV capture platform, which efficiently captured high-end digital data – exceeding the accuracy requirement detailed by the customer at project conception.

Our experience in underwater inspection in the energy sector drives our ability to hit the ground running, integrating effectively with the existing team and streamlining the scanning campaign.

The 3D outputs of the hull shapes were delivered to the engineering contractor, allowing them to use the geometry as a basis for the cofferdam and plug designs. This helped to negate the up-front dissemination of measurement data and proceed directly to pre-manufacture design tasks.

The Result

The project was completed successfully – we supplied the data required at unprecedented levels of accuracy, within a very short timescale. The engineering contractor now intends to use Viewport3 capture methods on similar projects in the future.

The project was instrumental in achieving our goal of displaying our capabilities to the industry – it aptly proved our claims that added value and operational efficiency can be realised by the deployment of simplified underwater scanning techniques.

The catalyst for a ground-breaking year at Viewport3, the completion of this task helped to propel our profile among operators and marine contractors.

In Numbers

Retrieving similar data using more traditional methods would take roughly three times as long in comparison to our in-house designed photogrammetry techniques. This type of project would typically take 21 days, whilst we completed the data capture in just 8 days.

Overall, we estimate savings to the operator of approximately 20 vessel-days, reducing the strain on IRM budgets and minimising the disruption caused by a lack of comprehensive drawing packages on older assets.