Congratulations to David for figuring out the sail plan (it had me bluffed.)
However, the builder seems to have rigged the boat with something a little more conventional. The actual set-up as seen in the photographs, seems to be nothing other than a conventional gaff sloop, the only odd thing being it is unstayed, except for a forestay to the stemhead, and a naked bowsprit. Perhaps the bowsprit is intended to be used for a flying jib or a ghoster or something like that, in light weather. As David pointed out, the "spinnaker pole" in the drawing doesn't look like a very good idea, but setting such a sail to the end of a bowsprit is not quite so impractical, if you want to fool around with that sort of thing in light weather.
I imagine the sole purpose of the forestay is to allow a moderate-size working staysail to be easily managed.
As actually set up, with gaff main and a staysail hanked to that forestay, it is not all that off-the-wall. You would never get the forestay as tight as some people would like, but it would be plenty good enough. It might quite possibly sail very well just as it is. As a plain gaff sloop it looks like a delightful proposition for sheltered shoal water. I don't think every boat with a free-standing mast necessarily has to be converted to a junk rig.
If you want a junk rig, David is right - but don't forget, an unstayed aluminium mast can easily be extended - extended aluminium poles seem to be de rigueur here in NZ, where we can't get tapered lamp poles. You don't need to settle for a short mast , though I don't think this little boat wants too large a sail area.
Couldn't resist spending 5 minutes to plonk some junk sail plans on this neat little adventure boat, with a slightly extended mast in its current position. The low AR Johanna sail looks good, to me. Actually, they all look a little too far forward on the hull, especially the SJR which looks plain wrong - but there are ways around every problem. (I would be interested to know what Arne thinks of the Johanna sail - with vertically raked mast and minimum balance through to a good forward rake and more balance - there seems to be enough scope for adjustment to get things just about right?)
