Whew! What a lot of comments, advice, critiques and ideas; too many to deal with, in truth!
I haven't concluded this thread until today because I wanted to have more time with the boat, and I've also happily been in places with poor Interent connections. If anyone responds to this post, I shall try to reply, but as SibLim is now FanShi, I think the thread has run its course.
Firstly, let me deal with the only negative that I have found: the lee helm. After trying all sorts of different variations, I finally concluded that what was needed was to move the sling point about 18 inches further forward. The top of the sail doesn't set perfectly, because the natural inclination of the yard is to sit at mid point, but it doesn't look too bad. Today Alan and I fiddled with the LHP which is now a bit of a cross between a THP and an LHP, going from the top sheeted batten back to itself and then down to a block. Set up with a reasonable, but not excessive, amount of vigour, it removes most of the creases; but the sail is more or less in the same place as it was in its previous setting, which I have now used on a couple of passages, covering about 40 or 50 miles in total. Yesterday I deliberately went out in very light airs and spent a fair bit of time on starboard, which is where the lee helm is/was most apparent. It is still there up until an honest F2, when it gradually disappears. Indeed, close-hauled in F3 I could leave the helm to look after itself and the boat sailed herself. I would guess she was sailing a bit more freely than ideal, but the real point is that she kept on course. I think all the junks that I have been shipmate with had lee helm in very light condtitions, and I am now perfectly happy with that aspect. The only other drawback, to me, is that the boom is very high aft. Alan can easily reach it, but I can't. That, in combination with the extreme camber, does make it difficult to work on the rig. I anticipated this to an extent and have the lazyjacks made off on cleats, with an eye in the end so that I can bend on an extra line and lower the sail down to a sensible level.
So what else? The boat is very stiff and has an unusual, corky, buoyant motion which reminds me a little of sailing a catamaran. It seemed very odd at first, but I am quickly getting used to it. She doesn't seem inclined to roll unless hit by a big wake, bang on the beam when the motion is as violent as it ever gets and things might even fall over. Generally they don't! I haven't observed her at anchor in any amount of wind, from another boat or from ashore, but on board she feels as though she doesn't sheer around too much, and she certainly doesn't sail to the end of her cable, lean over and then head back the ther way. Or at least she doesn't appear to, which is the main thing as far as onboard comfort and a sense of security are concerned.
The bilgeboards are easy to use; I don't think I get them as deep as David intended, but they seem more than adequate and FanShi - so far - has tacked without the slightest hesitation. Generally, they are quiet at anchor, unless it is very choppy, when little waves slap and crash in the boxes. Underway they are also quiet except in a beam sea when the noise can be quite appalling as they rattle and crash. However, if the board is raised properly it becomes a lot quieter and I am starting to think that when the lee one starts rattling, it is a hint that it's no longer doing anything and I might as well haul it up.
The balance in the sail, even though now somewhat reduced, makes for a soft gybe, as I had hoped. I'm happy with the weight of the yard - it brings the sail down easily, but is no effort to raise. I just hope that it is strong enough to stand the sling point being moved forward.
The boat tracks amazingly well, even with the boards up, but she is very sensitive to being overcanvassed and protests strongly if that happens. I reckon she and I are both happy to take the first reef at the top of F3 and the second and third come pretty quickly after that. I would say that the strongest gusts so far have been about F6 where she would really like to have 4 reefs. I like the shallow angle of the yard. My only concern is that they boat is perhaps too easily driven: I am a nervous sailor and don't really enjoy sailing at much over 5 knots. However, I have no intention of going out and looking for strong wind, either!
The self-steering gear is absolutely superb. It starts to work as soon as the boat is ctually moving with the wind, is sensitive and so easy to adjust - much better than the complexity of a servo-pendulum. The first time I tried it out was sailing down Whangarei Harbour with the lightest of breezes from dead astern. It held us on course without a problem. Originally there seemed to be too much friction, but I unlocked the trim tabs for 48 hours and let them swing back and forth and that seems to have sorted it out.
As for the poor, much-maligned engine, I have to say that having given it a couple of good, long runs, it seems to have decided that it might as well co-operate. Having squeezed the bulb and pulled the choke right out, I usually start it after 2 or 3 pulls. I can't say it takes much effort to turn it over. At first I needed to play the choke very arefully, but now I can just run it with the choke pulled out less than 10mm and after 3 or 4 minutes push it in completely. It idles more and more smoothly each time I use it I shall treat it to a new spark plug when I get the opportunity!
There is still, of course, lots and lots to learn. I don't really know how she goes to windward and certainly not in anything of a chop, but I'm happy with what I've seen. Overall, I think David has created something that ticks all the boxes. Indeed, I rather suspect that, with my penchant for reefing sooner rather than later, her sailing potential will be wasted on me. I'm sure she could surprise more than a few people in the local regattas, if I were prepared to push her. SibLim is completed and at this stage, I really hope that some sisters are built very soon! This seems like too good a boat only to have one incarnation!