抄録
The rowing of shell eight boat is studied hydrodynamically focussing on the forces generated by the oar blade. The speed and the rowing motion are analyzed by an image processing technique to provide the motion of the blade and the resultant velocity and the incident angle of the flow to the blade. The steady force acting on the blade is measured which is used for the estimation of the force generated by the blade by assuming that the rowing motion is quasi steady. Discussions are made to understand the mechanism of generation of the hydrodynamic forces by the oar blade. The steady drag coefficients by the blade are much affected by the angle of the incident flow to the blade surface and the resultant velocity; the maximum values appear when the angle of attack is between 40° and 140°. Free-surface effects are noticeable on the drag coefficients. The paths of the blade show that the blade moves mainly in the lateral direction to the still water and not so much in the longitudinal direction. The lateral motion generates the thrust. The angle of the incident flow to the blade delicately affects the thrust. The estimated thrust shows that the thrust changes during one stroke very much; high thrust is generated around the catch and the finish but it is minimum at the middle, while the efficiency is maximum around the middle. Three assumed patterns of rowing are simulated by estimating their thrusts and discussions are made for more efficient rowing techniques.
