I am working on v-ADCP data of marine currents in a port. I have data along transects and I want to create a 2d map with interpolation of data which shows direction and intensity of currents. I use surfer 13 and I created two grid for velocity and direction and then created a 2-grid vector layer, resulting in arrows that show the direction of the current with a scale color for velocity. the problem is that the interpolation creates data inside a polygon delimtated but my pool of data, so there is new data even in areas where I don't have any, for example on land and docks..how do I set an interpolation method which allows me to interpolate data only in an area along the transect? I tried kriging and Triangulation with Linear Interpolation methods. thank you

Anna