Experimental Study on the Drifting Speed of Inflatable Type Life Raft under the Wind at Sea

Abstract

This paper relates to some experiments with respect to the drifting speed of inflatable type life raft under the wind. Tests were carried out for model in the wind-tunnel with water tank and for actual raft at sea. Raft is used and that principal dimension and experimental conditions are shown in table 1. Hydrodynamic and and aerodynamic forces are measured in model test and the drifting speeds are observed in model and actual experiments. The tests results are as follows ; 1) The aerodynamic force increases with the square of wind speed linearly and the coefficients of the forces are shown in fig.1. 2) The hydrodynamic force increases with the square of drifting speed and the coefficients of the forces are shown in fig.2. 3) The drifting speed caluculated with the balancing of the aero and hydrodynamic forces is good agreement with the speed obtained by the drifting experiments of actual raft at sea. 4) The effect of sea anchor against the drifting of raft is not so expectable in practise as shown in fig.4.