As many years as I've messed around with a GoPro camera I've never managed to build a good "mast tip mount" to shoot "bird's-eye view" windsurfing video. I finally got around to it this weekend, putting the camera mount on top of my 9.5 Ezzy Cheetah.
To start with, I drilled holes in the corners of a GoPro base plate- just wide enough to put a piece of coat hanger wire through. Then I snaked bits of coat hanger wire through the holes, through the slot in the top of the mast cap, and around the base of the mast cap, bending them so that they would hold securely. I cropped the ends of the wire and wrapped bits of tape around them so they wouldn't scratch the sail. It wasn't pretty, but it held securely, and I got what I think is some pretty good footage.
The session was at Wiggins Pass State Park, in offshore winds gusting around 15 knots, on my Bic v1.2 Formula board with a 58 cm fin. The song in the video is by U2.
Mast Mount May 2013 from James Douglass on Vimeo.