A METHOD TO DETERMINE THE MOMENT OF BUOYANT FORCE ACTING ON FRONT-CRAWL SWIMMERS

  • T. Yanai
Keywords: body-roll, density, centre of buoyancy, frustrum of cone, sensitivity analysis

Abstract

The purpose of this study was to develop a method to determine the moment of buoyant force acting on a front-crawl swimmer about the longitudinal-axis (buoyancy torque). The buoyancy torque was determined using three-dimensional kinematic data of one swimming trial and the dimensions of the body segments. Each body segment was modelled as a frustrum of cone, whose dimension matched the body segment parameters (relative mass, density, and centroid) reported in the literature. The buoyancy torque was found to attain its peak value (13 Nm) in the middle of the recovery phase. Sensitivity tests revealed that the individual variability in the body segment parameters would make small effects (< 3 %) on the buoyancy torque. With this method, the effect of buoyant force on body-roll can be determined to a known degree of accuracy.