Abstract
When let go anchor and make it bring up or when moor on anchor in strong wind, the forces acting on anchor are dynamical ones caused by ships motion, so we have investigated the behaviours of anchors on sand bottom in such circumstances by model experiments. The results of experiments are as follows: -1) when we make anchor bring up, ship's speed affects on the behaviour of anchor biting into bottom. And if we can measure always the tension of anchor cable, it may be able to judge whether the anchor brings up effectively or not. 2) when the dynamical forces act on anchor having brought up effectively, the anchor is dredged quickly but it does not rotate or jump out the bottom. When the dynamical force is over, the anchor bring up effectvely as in initial condition. The length of dredging is not so long as several times of anchor lenght. The resistance of anchor in this circumstances, we could not analyze theoretically but we have to study hereafter experimentaly or theoretically.
