Offshore Wind Farm - View from shore

BOEM Proposes Rule Changes to Defer and Streamline Surveys

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The proposed rule changes allow for the delay of geotechnical surveys and shift geophysical surveys from a prescriptive approach to a performance-based requirement.  Offshore wind survey companies will have the latitude to approach deliverables using new and varied technologies.  This presents both risk and opportunity.

Offshore Wind Farm - View from shore“Before constructing an offshore renewable energy project, lessees and grant holders must conduct geotechnical, geophysical, and archaeological surveys. The primary purposes of these surveys are to ensure the site is suitable for construction, avoid seafloor hazards, and identify historic and cultural resources. Currently, BOEM requires detailed geotechnical survey data for each proposed wind turbine location in the construction and operations plan (COP) submitted by the lessee before project construction is authorized. However, the Department has learned that the precise location of each wind turbine may be uncertain at the COP submittal stage, and geotechnical data collected primarily for engineering purposes are more relevant to the review process after COP approval. Consequently, lessees have requested permission to submit geotechnical data for each turbine location after COP approval, but before construction. This proposed rule would defer certain geotechnical survey requirements, such as engineering site specific surveys (e.g., boreholes, vibracores, grab samplers, cone penetrometer tests and other penetrative methods). This proposed change would allow more time to complete the required surveys and would provide greater flexibility in designing projects.”

“The survey and data collection requirements would shift from the largely prescriptive standards in the existing regulation to performance-based standards. These performance-based standards would give lessees the leeway to demonstrate that their selected combination of geotechnical and geophysical surveys provide BOEM the data that it needs at the COP review stage to determine
whether the project as designed can be constructed safely in the proposed range of locations—assuming industry standard engineering practices are used at subsequent phases.

Pricus Marine supports offshore wind survey firms with purpose built vessels and equipment on a charter/rental basis.

Proposed rule changes linked here:

https://www.govinfo.gov/content/pkg/FR-2023-01-30/pdf/2023-00668.pdf

Multibeam Roll vs Swath Width - how roll kills hydrographic survey productivity

Roll Stabilization Makes You Money … if you are a hydrographic surveyor

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Bottom Line Up Front:  A vessel that rolls less covers more ground…273% more in this case.

Modern multibeam echo sounders are incredible in that they can use beam steering to counteract roll motions in order to maintain the swath of a survey line.  But….there’s always a catch.  Beam steering can only occur within the bounds of the multibeam echo sounder’s maximum swath angle (160° in this case).  If you have a stable vessel that exhibits roll within -3° to 3°, you can theoretically still utilize 154° of your maximum swath angle.  In contrast, if your vessel experiences -30° to 30° of roll, even if only occasionally, only 100° of swath angle could be used.

This graph illustrates how a survey vessel’s roll impacts the maximum swath width of a multibeam echo sounder.  While required sounding density and other factors may also influence swath widths, they can never be wider than the motion of the vessel permits.

The graph compares the effect of roll amplitudes on maximum multibeam swath widths in 50m water depth.  The callouts are to illustrate the relative performance of different hull types in a 2m sea state.  There is a 273% increase in swath width when comparing a 150° swath angle with a 100° swath angle.  Simply put; a 14 day job for a less stable vessel could be a 5 day job for a more stable vessel.  When you think about the implications roll on Health Safety & Environment (HSE) and ultimately on profitability, it is imprudent to ignore.

Be sure to follow Pricus Marine on Linkedin at https://www.linkedin.com/company/pricus-marine-llc/

Learn more about how Pricus Marine is using SWATH vessels to deliver outsized value to our clients at pricusmarine.com

Check out some of the hydrographic equipment that we have to offer in this article:  https://pricusmarine.com/pricus-marine-adds-multibeam-echosounders-inertial-navigation-systems-and-sound-velocity-profilers-to-their-equipment-pool/