America’s Cup is the oldest competing trophy in sport between defenders and challengers. Because of the history and prestige of American’s Cup, the world’s top sailors, yacht designers and wealthy sponsors are attracted to this popular and perpetual international competition.

To make a great achievement, different roles of the crew do their best to complete special tasks and in addition the equipments have to fit the crew. For instance, the grinders as the main role in the crew, the winches that the grinders work with are required to design to match the grinders’ own anthropometric characteristics to allow fast sail handling.

Owing to the correlations between crank-axle height and stature, crank arm length and arm span, this project aims to investigate the optimum combination of crank-axle height and crank arm length according to the percentage of stature and arm span. Subjects perform forward standing grinding with maximum effort for a certain time against a particular resistance. Experiment equipments are designed with SolidWorks, experiment data is recorded via Kick and data analysis is finished by Matlab codes.

From the result of experiment, overall, it could be concluded that the generally optimum combination is 10-10.5 % of arm span and 60-62 % of stature. However, it only works on forward grinding. In America’s Cup, two grinders perform both forward and backward grinding together at one winch, the optimum combination that can be applied in backward grinding should be tested in the next step.