Abstract
In this paper, we deal with the hydrodynamic properties of VOS (volunteer observing ship)
to lend itself for direct monitoring of seawater. The original depth of seawater sampled at the
stern at mid draft of the ship of opportunity for monitoring was estimated by model ship in an
experimental basin. We inject dye from the upstream of the model ship and pick the water up
from the inlet (sea chest), and then the density occupation rate of dye in the water taken from
the fixed inlet is analyzed by use of a spectrophotometer. By iterating the same sort of meas
urements changing the location of the dye injection point, we obtained a contour map of the oc
cupation rate of dye. Furthermore, CFD (computational fluid dynamics) was employed to
confirm the model experiment. The experiment in regular waves was conducted to make above
method extend to be applicable in real ocean condition. In addition, full size numerical compu
tation was performed to validate the new method in its practical use. Results showed that the
sampled water comes from near the water surface. In the scale of ferry being used for monitor
ing, it was predicted that water at -0.7m is drawn into the inlet at -4 to -5m in depth.
