They went missing for awhile....
Just a note that the mast angle in the plans is a 10 degree angle.
The design and drawings.... Thanks to Paul Day (Lake Lefroy Land Yacht Club)
The plans suit home builders and DIY people.
If you do build a yacht from the plans please post on Seabreeze with pictures of what you have done..... Thanks.
More construction info... (thanks SN)
Use the 60 x 2 tube, like Gizmo said - it is literally "available on every street corner" 
Not shown in the plans as these improvements were developed at a later date :
: mast step can be vertical [instead of the 10 degree rearwards lean] - this has proven to work very well with unmodified windsurfer sails.
: weld a plate over the rear of the chassis spine tube - then the tube is less liable to tear at the axle tube welds due to twisting.
: run a steel strap [flat bar 25mm ish x 5mm ish] down one side of the mast-step, underneath the chassis spine, and back up the other side of the mast-step.
Stitch weld the strap to the mast-step and chassis spine, not a continuous weld.
This will prevent the mast step welds from fatiguing and tearing apart due to stress.
