Abstract
Buoyancy of the expandable polystryrene float for raft type culture decreases as time passes in sea water. The float was immersed in sea water for periods of time varying from 5 to 600 days. The experiments were carried out in order to investigate the behavior of the buoyancy of the float under conditions as close as possible to actual use. The empirical formula which can predict the relation between the buoyancy of the float and the days of use in sea water was derived using ex-perimental values.
The results Showed that the buoyancy of the float decreased almost exponentially under the infiltration of sea water until 90 days after the start of measurements, and then decreased gradually with the deterioration of the float due to the erosion after 90 days. After 600 days of immersing the float in sea water, the buoyancy decrease was 16% of initial values.
