Tacking maneuver is an important aspect of sailing competitions. In general, two types of tacking（flat tacking and roll tacking）maneuvers are performed during the upwind leg. In this study, using a GPS in a small yacht of the laser radial class at sea, we quantitatively evaluated the tacking skills involved in these two types of maneuvers, and clarified the difference between them. Thirteen sailing athletes took part in the evaluation．Wind speed conditions were categorized as light wind (2-4 m/s) and medium wind (4-6 m/s). Tacking determined the analysis items and the definition of various variables according to previous studies.
The results showed that tacking time was shorter during roll tacking than during flat tacking. The distance covered during roll tacking was greater than that during flat tacking. Further, the boat speed during roll tacking was higher than that during flat tacking (light wind: 5.3%; medium wind: 2.8％). The results quantitatively showed that roll tacking was more effective than flat tacking in light wind and medium wind, and that the evaluation of redirecting capacity and the abovementioned training would be possible by using the evaluation method of this study in the future.
