# GNSS Applications to Assess Performance in Olympic Sailors: Laser Class
## 1 Introduction  
Dinghy sailing is a sport with specific characteristics, since performance will not only be determined by the level of physical fitness of the sailor, but also by the characteristics of the boat and the weather conditions [1, 2]. Therefore, Olympic sailing is a complex sport in which performance is determined by the ability to understand and anticipate the weather conditions, having adequate equipment for the boat (e.g., quality sails), and the mastering of the technique and tactics [3]. In addition, the level of physical fitness of the sailor is part of the general performance, and the physical and physiological requirements (muscular strength, muscular endurance, and aerobic and anaerobic capacity) have changed due to the increase in the level of international competition and the modifications that resulted from the Olympic navigation format [4]. Among the different Olympic classes, the sailors in the Laser class are considered dynamic hikers, since, due to a high sailor-to-yacht weight ratio, they are required to sail the boat in a very dynamic manner [5]. This monohulled-type class was designed by [PERSON] in 1969 and it is manned by a single athlete [6]. The Laser class is a one-person keel-boat: the weight of the boat is 59 kg, the overall length is 4.23 m, the beam length is 1.37 m and the sail in the Olympic category is different for men and women. Women compete in the Radial (5.76 m\({}^{2}\)) category and men compete in the Standard (7.06 m\({}^{2}\)) category. This is an Olympic class since 1996 and sailors compete under the One Design rule. The One Design class is controlled by World-Sailing(r) and the class rules are written to prevent any changes from the manufactured boat that might affect performance, ensuring that all thecompeting boats are the same [7]. This rule states that all sailors must compete with the same boats and sails and, thus, under the same conditions. In dinghy sailing, technique (velocity) and tactics (distance and maneuvers) determine factors related to performance in the regatta [8; 9]. The sailor's technique determines the velocity of the boat, and the VMG on the windward and leeward courses is considered the most important variable in a regatta, since the courses of a dinghy sailing are relatively simple and well defined, and, in many windward-leeward courses, two legs are navigated, one windward (upwind) and the other one leeward (broad reach and downwind) [10; 11]. The distance traveled during the regatta is a tactical variable that determines the performance of the sailor, since higher level sailors complete the course in shorter distances [8; 9]. The maneuvers influence the performance of the boat, since speed decreases when they are carried out, thus the sailor must decide when to perform them, and he/she must do it efficiently in order to minimize the loss of speed [12]. Since 2003, GNSS have consolidated their application in different sports and provide very relevant information on the external load, the movements carried out, and the physical activity of the athlete in training and in competition [12; 13; 14]. Several studies have demonstrated the validity and reliability of these devices to record technical and tactical variables in the windsurfing and kitesurfing classes [8; 9; 15]. Regarding performance, several studies have analyzed the relationship between performance and the sailor's physical fitness [4; 16], biomechanics [11; 17; 18; 19; 20], and psychological factors [21; 22; 23]. However, to our knowledge, not all aspects of technical and tactical performance have been thoroughly examined in dinghy sailing. The VMG, the distance traveled, and the maneuvers carried out in a regatta and their relationship with performance have only been evaluated in the windsurfing and kitesurfing classes [9; 10; 11; 12], and it is still unknown which course (upwind, broad reach, and downwind) is the most decisive for performance.