A sailboat is a strongly non-linear system that however has been proven to be easily controllable. Indeed, its mechanical design comes from an evolution from thousands of years with two main concerns: having a fast, reliable and ef cient vehicle while being easily controlled by humans. This article describes the functioning, the validation process and the performances of a simple controller, inspired from what navigators do, through tests made on the sailboat robot VAIMOS built by IFREMER for oceanography. This controller requires tweaking few parameters with real physical meaning while ensuring accurate trajectory following, needed to make oceanographic measurements in a speci c area.