Metocean reference document development
Metocean design basis and site condition reports that set out the conditions a project must be designed for.
Every offshore and coastal structure is designed against a set of environmental conditions. Those conditions are written down in a metocean reference document, often called the metocean design basis or site conditions report. Geomarins develops these documents, drawing on measured data, model hindcasts and recognised industry methods.
What a metocean design basis contains
- A description of the site, water depth and data sources used
- Normal (operational) conditions: the statistics of waves, wind, currents and water levels through the year
- Extreme conditions: estimated 1, 10, 50, 100-year and longer return period values
- Joint conditions: how waves, wind and currents combine, and from which directions
- Water levels: tide ranges, storm surge and design water levels
- Other parameters such as air and sea temperature, salinity, marine growth and visibility where needed
- Operational criteria and weather windows for installation and maintenance
Why it matters
The design basis is the agreed starting point for structural, mooring, pipeline and coastal engineering. If it is too optimistic, structures may be under-designed; if it is too cautious, the project carries cost it does not need. A clear, well-supported document also makes approval by certifying authorities, insurers and regulators easier.
How we develop it
We start by agreeing the scope with your engineering team: which parameters, return periods and directions the design needs. We then gather and check the data, run the analyses and write the document in a structure that engineers can use directly, with every number traceable to its source and method. Drafts are reviewed with your team before the document is issued.
Methods follow recognised practice for metocean conditions, such as ISO 19901-1 and DNV-RP-C205, and any client or project specification.
Updating the basis
As a project moves on, new measurements arrive. A design basis written from model data at the concept stage can be updated once a measurement campaign has run, often tightening the design values and reducing uncertainty.
What you get
- Metocean design basis document
- Site conditions report
- Operational criteria and weather window tables
- Extreme and normal condition tables by direction
- Design water levels: tide and surge
- Traceable sources and methods for every value
Frequently asked questions
What standards do you follow?
We follow recognised practice for metocean conditions, such as ISO 19901-1 and DNV-RP-C205, together with your project or client specification.
Can a design basis be written without measured data?
Yes, at early stages it can be based on model hindcasts and regional data. It is best updated once site measurements are available.