Hydrographic Guidelines for Offshore Developers

Introduction

The following guidelines are intended to aid developers when submitting consent applications which impact upon hydrography.  In addition, the Maritime & Coastguard Agency are always happy to give help and advice on hydrographic data gathering requirements in order to increase the usefulness of hydrographic survey data and improve navigational safety.  

In addition to the following guidelines, developers of offshore renewable energy installations should also consult section 6 of Annex 2 of Marine Guidance Note 371 "Offshore Renewable Energy Installations (OREIs) Guidance on UK Navigational Practice, Safety and Emergency Response Issues."

Survey Requirements

The survey should meet the requirements of IHO S44 Order 1 in every respect.  Particular attention should be given to horizontal and vertical sounding accuracy, together with target detection requirements.  A report should describe how the data was gathered and processed.

The following requirements should be met:

  • All data should be rendered in digital form. Ideally, this should be in one of the following formats: Caris HDCS directory (i.e. “HIPS”); Simrad PROC directory, Generic Sensor Format or Fledermaus PFM; but simple ASCII “xyz” is acceptable if the other formats are not available.
  • If a hard copy plot and/or .dwg drawing is available, please also supply that, as it helps UKHO to check that the digital data is complete. Drawings may also include useful non-bathymetric detail, such as coastline and details of construction projects. Please record any differences between the digital data and the drawing, especially if depths on the drawing have been edited, but the edits have not been applied to the digital data.
  • Spurious data should be cleaned from the final, delivered, dataset.  Digital data should have rejected soundings included, but flagged as deleted. The method used in any data-cleaning (e.g. Shoal or Median Biased) should be clearly stated.
  • Digital data should be full density (i.e. prior to any gridding, binning or tinning being applied).
  • The soundings should be reduced using observed tides (not predicted tides from Tide Tables).
  • Depths should be referenced to UKHO Chart Datum for the area.

A report should be submitted with the survey data.  The report should include:

  • A list of the equipment and software used, and the personnel involved.
  • How positioning equipment was set up, calibrated and used
  • How the echo-sounder transducer was set up and levelled, together with all sensor offsets.
  • Details of the horizontal datum to which the positions are referred (or the grid, if appropriate).
  • Details of the tidal datum to which the depths have been reduced.
  • How tides were measured, how the tide pole or tide gauge was leveled and how depths were reduced to chart datum. NB a leveling diagram is a useful method of confirming that datum adjustments have been carried out correctly.

Reports written in the Royal Navy “Electronic Report of Survey” Microsoft Word template would be ideal (template available on request).

On completion of the survey, all the above data and reports should be sent to:

Hydrography Manager
The Maritime & Coastguard Agency
Bay 2/30, Spring Place
105, Commercial Rd
Southampton
SO15 1EG

If you require any assistance with the above requirements, please contact the MCA at:

navigationsafety@mcga.gov.uk