The work achieved with the sail dynamometer boat “Fujin”, and the role of full scale tests as the bridge between model tests and CFD

•Sail shapes and performance for upwind conditions were measured.•Sail shape database provides a good benchmark for the validation of sail CFD.•A new simulation model of tacking maneuver was proposed.•The simulated results showed good agreement with the measured data.•Full scale tests using a sail dynamometer boat are free from scale effect.

The work achieved with the sail dynamometer boat Fujin was reported. At first, the sail shapes and performance for upwind conditions were measured in steady sailing conditions. The results were compared with the numerical calculations. The database of three-dimensional coordinates of the sail shapes was also tabulated with the aerodynamic coefficients. The sail shape database provides a good benchmark for the validation of sail CFD in full scale level. Then, the aerodynamic force variation during tacking maneuvers was measured by Fujin, and a new simulation model of tacking maneuver was proposed. The simulated results showed good agreement with the measured data. Finally, the scale effect problem of wind tunnel tests was discussed. Wind Tunnel tests using model sails are performed at the region of critical Reynolds number. Therefore, the wind tunnel test had to be performed very carefully. On the other hand, the full scale tests using a sail dynamometer boat are free from scale effect problems and appear more promising.