We measured the drag of three different boards at different speeds in order to find out which type and length of board requires which energy. Here is the result:
And here is a video, which shows how the measurement was done. We used an mechanical and electrical scale and also measured the time between two points giving the speed. The operator for the pulling-cable speed entered a constant speed over the entire measurement track.
Video showing measurement
The wave board was a Slingshot wave board for kite-boarding. The second board was an old surfboard. The SUP was an inflatable SUP, which is shown in the video.