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The full-scale beta version was built in spring 2000. The material was aluminum for minimizing weight. It is made of two parts, the lower one which is from 20m to 9m below the surface and consists of the sphere and a simple tubular structure, and the upper one which goes from 9m below the surface to 4.5m above the surface, and which hosts the instrumentation.

The full-scale beta version has been deployed on site during three months (20 July to 20 October 2000), which allowed to encounter a variety of meteorological situations. The buoy was equipped with two inclinometers, a pressure sensor, an ARGOS beacon and a flashlight. The goal of this deployment was to qualify the new concept of buoy as well as to identify possible problems necessitating modifications. Fig. 7 shows the full mooring on the deck of the ship before it is deployed. A full day was necessary for the deployment operations, which as well are totally new with respect to what is usually performed for classical moorings. The details of these operations are not given here.

The complete mooring line on the deck of the ship, before deployment (beginning of operations : July 20, 2000 ; 7 am)

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The results of this deployment are shown in Figs. 8 and 9. Without entering into out-of-scope details, the following comments can be made (refer to the figure legends):

  • From mid-September to the end of the deployment, the conditions were quite rough (mean swells up to 4m, which means at least 5m peaks).
  • Until mid-September, the periods where the buoy is inclined at angles larger than 5o is small, which means that the beta version was already satisfying the requirements for meteorological conditions from calm to moderate.
  • Oscillations are observed, which exactly match the inertial period of the ocean at the latitude of the site. These oscillations are due to oscillations of the water masses after the wind stress is relaxed.

In summary, the results of the qualification deployment showed a certain lack of righting torque, with consequences on the behavior of the buoy when the swell becomes greater than about 2m. Although not dramatic, this behavior is not totally satisfactory, so that it was decided to introduce slight modifications in the design and construction of the buoy in order to improve the percentage of time for which the requirements in terms of inclination is satisfied.

Results of the qualification deployment (July 20 to October 20, 2000), showing the time series of (a) the depth of the buoy CTD (nominally at 8.3 meters when the buoy is motionless and the sea surface perfectly flat), (b) the buoy tilt, (c) the swell height, (d) the swell period, and (e) the wind speed.


Percentage of the tilt measurements that were lower than 5 degrees, as computed over successive decades of the qualification deployment.

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