Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999 15-19 octobre 1999
Résumé : In Curacao, deep-water fads with grp surface buoys were developed and tested. The first fad was deployed in 1993. Up to now, a total of 5 fads were deployed at the following depths: 730, 685, 700, 754 and 574 metres. Changes were made to the surface buoy, resulting in an improved design, the mkii surface buoy. One fad lasted three years and one month. The main features of the design used are: the use of a sparbuoy design with constant tension on the moving chain to avoid slamming and jerking of the surface buoy; liberal use of sacrificial anodes, and maintenance to replace these anodes about once a year; the use of a short anchor chain with depth buoys, that does not touch bottom; a one-piece inverted mushroom anchor. With the grp surface buoy, a reserve buoyancy of approximately 800 kg is obtained with chain as external ballast about 610 kg of net buoyancy remains (it would seem that the reserve buoyancy needed where strong currents occur, has been underestimated in many designs). Five new grp mkii buoys are now under construction. Utilizing the experience gained with the deep-water fads, two new types of fads made of 500 mm diameter pvc tubes were designed to be used in waters of shallow and medium depth (150-400 m). One design uses a 3-m length of pvc tube, the other a 5-m tube (500 mm diameter). One fad with 3-m pvc buoy has been tested succesfully, two 5-m pvc buoys are under construction. The use of pvc results in a buoy which is substantially less expensive than a grp buoy. On the other hand, this type of buoy can probably not withstand the same forces as a grp buoy and we assume that for use in deeper waters the grp mkii buoy will still be needed.

Droits : Ifremer
http://archimer.ifremer.fr/doc/00042/15288/12674.pdf
http://archimer.ifremer.fr/doc/00042/15288/