Making the mast round:  The base is  85mm square for about 250mm  . Then progresses from a diameter of 75mm to  a diameter 85mm (about the middle).  It then tapers to a diameter of 60mm at the top of the mast.  If you are interested in the geometry of making a mast go to http://www.wikihow.com/Make-a-Solid-Boat-Mast

September– October 2011