Wave radar
General information
The waves, wind and current conditions are the drivers of the design and engineering of platforms, as they provide important design criteria, which are normally based on historical statistics. Long term monitoring of the environmental conditions have already shown that these criteria often have to be reviewed and updated.
Accurate information on the environmental conditions is also of importance for the operational performance and safety on board of ships and offshore structures. Wind speed and direction are essential for helicopter operations, whereas wave and current information is crucial for supply boats, divers and maintenance jobs.
The waves, wind and current conditions are the drivers of the design and engineering of platforms, as they provide important design criteria, which are normally based on historical statistics. Long term monitoring of the environmental conditions have already shown that these criteria often have to be reviewed and updated.
Accurate information on the environmental conditions is also of importance for the operational performance and safety on board of ships and offshore structures. Wind speed and direction are essential for helicopter operations, whereas wave and current information is crucial for supply boats, divers and maintenance jobs.
Service & Activities
The environmental conditions can be measured using a wide range of instruments. For each particular application the most suitable instrument can be selected, based on duration of the measurement campaign, available power, required accuracy, etc. MARIN can assist in selection of the proper instrument for the job.
For the interpretation of the recorded waves, wind and current it is important to understand the associated platform behavior. By combining measured waves, wind and current with measured platform responses (motions and loads) this information can be derived in dimensionless form, such as response amplitude operators and load transfer functions. These are required to verify design data and methods. Time traces of waves, wind and current are required in order to do deterministic time domain simulations.
It should be noted that the duration, sampling rate and processing of the environmental conditions should be related to the aspects under investigation. In particular low frequency excitation of the motions requires special processing.
The environmental conditions can be measured using a wide range of instruments. For each particular application the most suitable instrument can be selected, based on duration of the measurement campaign, available power, required accuracy, etc. MARIN can assist in selection of the proper instrument for the job.
For the interpretation of the recorded waves, wind and current it is important to understand the associated platform behavior. By combining measured waves, wind and current with measured platform responses (motions and loads) this information can be derived in dimensionless form, such as response amplitude operators and load transfer functions. These are required to verify design data and methods. Time traces of waves, wind and current are required in order to do deterministic time domain simulations.
It should be noted that the duration, sampling rate and processing of the environmental conditions should be related to the aspects under investigation. In particular low frequency excitation of the motions requires special processing.
Facilities & Tools
Full scale wave, wind and current measurements are carried out by MARINs Trials & Monitoring department.
Waves can be measured using different instruments, each with their own benefits and drawbacks. Examples are:
Full scale wave, wind and current measurements are carried out by MARINs Trials & Monitoring department.
Waves can be measured using different instruments, each with their own benefits and drawbacks. Examples are:
- Wave rider buoys provide accurate waves information at a specific location. However, the wave rider buoys must be moored and can be lost due to bad weather and collisions by other ships. Furtermore, due to its mooring the wave information is valid for one location only and hence not practical for sailing vessels.
- Wave radars measure the relative wave height. This has to be compensated with the local vertical motion of the radar in order to derive the absolute wave height. Combining the signals of at least three distributed wave radars, the full 3-D directional wave spectrum can be derived.
Wind speed and direction can be measured using the following devices:
- Propeller type anemometers with vane. In hurricane conditions these sensors are often damaged, which results in loss of data.
- Solid state accoustic sensors, which measure wind speed in two or three components. These are currently favored, becasue of their robustness.
Accoustic measurements are the state-of-the-art in shallow water and deepwater current measurements. Accoustic Doppler Current Profilers (ADCPs) have proven their accuracy and robustness for measuring the current speed and direction up to a depth of 1000 m below the surface. Low frequency ADCPs can be used to achieve maximum range, whereas higher frequency ADCPs will have lower range but increased resolution. Attention should be paid during installation of the ADCP on an offshore structure, as neighbouring structures (such as columns, risers and tendons) may distort the ADCP readings due to reflections. In case the full water column can not be covered by one single surface ADCP an upward looking ADCP can be mounted in a sub-sea buoy moored just above the sea floor. Recovery of the bottom ADCP is done by means of an accoustic release, on average once per 6 months. Horizontal ADCPs can also be used to measure the surface currents as well as the wave profile.
Wave, wind and current measurements at model scale are carried out by the Offshore department and the Seakeeping department in the following facilities:
Software Sales
Some software tools are available for commercial use outside MARIN. A complete overview of these software tools for sale can be found under Software Sales.
Some software tools are available for commercial use outside MARIN. A complete overview of these software tools for sale can be found under Software Sales.
Experience record
The list below gives a review of wave, wind and current monitoring projects carried out at MARIN:
The list below gives a review of wave, wind and current monitoring projects carried out at MARIN:
- Marco Polo JIP (10 companies), Marco Polo monitoring & analysis, 2005 – 2007
- Kahn Shipping, Wave, acceleration and lashing load monitoring Fairpartner & Jumbo Javelin, 2005
- Dockwise/Petrobras, Wave and motion monitoring P-40 transportation, 2001
Publications
Papers on wave, wind and current measurements by MARIN are:
(Complete overview of papers can be found under Publications)
Papers on wave, wind and current measurements by MARIN are:
(Complete overview of papers can be found under Publications)
Model Test Investigation of LNG Tandem Offloading with Dynamic Positioned Shuttle Tankers
Jaap de Wilde, Jorrit-Jan Serraris, Erik-Jan de Ridder (MARIN), Marie-Laure Bécel and Jean-Robert Fournier (SBM Offshore), OMAE Conference, Shanghai, 2010
Effect of Variations in Calibrated Wave Parameters on Wave Crest and Height Distributions
Janou Hennig and Jule Scharnke (MARIN), OMAE Conference, Shanghai, 2010
Prediction of Wave Crest and Height Distributions and Wave Groups using a Numerical Wave Tank
Christian Schmittner (MARIN), Sascha Kosleck (TU Berlin) and Janou Hennig (MARIN), OMAE Conference, Shanghai, 2010
Jaap de Wilde, Jorrit-Jan Serraris, Erik-Jan de Ridder (MARIN), Marie-Laure Bécel and Jean-Robert Fournier (SBM Offshore), OMAE Conference, Shanghai, 2010
Effect of Variations in Calibrated Wave Parameters on Wave Crest and Height Distributions
Janou Hennig and Jule Scharnke (MARIN), OMAE Conference, Shanghai, 2010
Prediction of Wave Crest and Height Distributions and Wave Groups using a Numerical Wave Tank
Christian Schmittner (MARIN), Sascha Kosleck (TU Berlin) and Janou Hennig (MARIN), OMAE Conference, Shanghai, 2010
Articles for MARIN report on wave, wind and current measurements by MARIN are:
(Complete overview of articles can be found under Publications)
(Complete overview of articles can be found under Publications)
Determining wind loads with CFD
Arjen Koop, MARIN Report, 2011
The Blue Revolution is coming!
Guilhem Gaillarde, MARIN Report, 2011
World-class deepwater Anchor Handling Simulator
MARIN Report, 2011
Arjen Koop, MARIN Report, 2011
The Blue Revolution is coming!
Guilhem Gaillarde, MARIN Report, 2011
World-class deepwater Anchor Handling Simulator
MARIN Report, 2011
Contact
For more information on full scale waves, wind & current measurements please contact Trials & Monitoring department.
For information on model test wave, wind and current measurements please contact the Offshore department or the Seakeeping department.
For more information on full scale waves, wind & current measurements please contact Trials & Monitoring department.
For information on model test wave, wind and current measurements please contact the Offshore department or the Seakeeping department.