Analysis of the Influence of Sail Angle and Wind Direction on Sandeq Boat Speed

Abstract

Sandeq is a traditional sailing boat of the Mandar community, characterized by a slender hull, outriggers for balance, and a sail as its main source of propulsion. Sailing performance is affected by the interaction between wind direction and sail-angle setting. This study aims to analyze the effect of sail angle and wind direction on Sandeq boat speed based on field observations at sea. The study employed a field-experiment and naturalistic-observation approach using an actual Sandeq boat during an expedition along the coastal waters of Sulawesi. The observed variables included sail angle, wind direction and speed, travel distance, and sailing time. Boat speed was calculated as the ratio of travel distance to travel time, while the relationship among variables was described and analyzed using linear regression as reported in the source thesis. Four sail-angle conditions were observed: 40°, 45°, 60°, and 67°. The reported average boat speeds were 9.5, 5.4, 8.8, and 9.7 km/h, respectively. The field observations indicate that changes in wind direction and sail-angle setting are associated with changes in boat speed. These findings provide a basis for technical documentation of Sandeq operation and for further studies incorporating wave conditions, boat loading, helmsman skill, and more controlled wind and position measurements.