I don't know of a video tutorial (yet) but it is easy to do. Suppose you want the base of the mast of the rear boat to be the origin. Then just open the autotracker, set the target to axes origin, shift-click the mast base to mark a key frame and hit the Search button. Tracker will automatically set "fixed origin" to false so the origin can track the mast. It's really no different than autotracking a point mass--the autotracker just finds the best match and then "marks" whatever point is targeted.  Of course you could also do this with the mouse (drag origin or select it and shift-click the mouse where you want to place it), but in the case of the axes the video doesn't autostep to the next frame so autotracking is much easier. Doug