David Tyler wrote: Doesn't this remind you of Passe Patu's sails, Annie? I seem to recall you saying how bad at snagging their sheets they were with a tapered planform, and how they really had to be recut to have their luffs and leeches parallel.

From my experience, curved leech can give problems.  I don't think the luff would be an issue, on a single-masted boat, but I suspect you might have to extend the battens at the leech in order to stop snagging.  But I assumed Chris had thought about this and was making a model of the sail as such, rather than how it would look when complete.  No doubt he will use longer battens in real life, to prevent the sheets catching.

Chris’ proposed rig is looking good, for sure, but...

frankly, if I were to make a split JR, I would aim for a planform very close to that of Slieve’s Poppy. It may not look as elegant as this elliptical planform, but the Poppy rig has three advantages:

·         Many identical panels makes the lofting and sewing job a lot easier.

·         A sail, which is wider higher up, adds sail area, and a generous sail area is very useful for downwind sailing, something we do a lot of the time.

·         The vertical leech prevents the sheetlets from getting caught by the batten ends or under the boom, when tacking or gybing.

Boring arguments, maybe, but that is how I am wired:

“Easy handling beats performance,
and
 performance beats fancy looks”...

Me again...

Arne

Always sceptical of computer models, I have made a 'stick and string' model of the rig at a scale of 1:12, using 12mm, 8mm and 5mm dowels. Halyard, lower sheet and spanned downhauls in place.

Chris

Not having any experience of Junks or Junk rigs or aerodynamics, but an avid follower of this website, I was interested in you idea of using mesh at the leach of the jiblets of your proposed rig. I don't know if it's applicable but a few years ago I spoke to man who was involved in spraying foam insulation on the outside of roofs of buildings and I asked how, on windy days, they stopped the wind blowing the spray all over the place, and he said that they hung a net around the work area and this was sufficient to reduce the wind speed. I wonder if the mesh would do the same and reduce the airflow.

 Thinking about it it would be like the drag of the wires and struts on a bi-plane.

P.S.Beautiful photo

"Would this be workable? And useful?"

Chris, I believe you are asking the right questions here.

It is in our interest to build the most efficient rig we can think off, but then remove as many of the complications as we can. Since the start with the split rig I have experimented with additional jib leech sheets and mini-sheets, and believe there is some gain to be made, but at what cost? On Amiina's latest rig the sails are placed on the centre line of the battens and not to the outside or inside so that a light sheetlet can be attached to the leech of the jib and the luff of the main panel and have equal tension on both tacks. We also added short batten pockets to the centre line of each jib to experiment with short bendy battens to help pull in the centre of the leech and have played around with this setup. 

Without a second identical boat to sail against it is so difficult (read impossible) to judge if there is any significant gain from such experiments, so we have always ended up with your expression above "and useful?". I am a fully paid up member of the "KISS" system, and the junk rig encourages this attitude. We seem to be getting adequate performance without the added complication, and having considered an open mesh in the past I have been concerned that it might 'hook' the leech of the jib which I believe we do not want, so have not tried it. It would be great if someone tried it, but it is more complication. (Thinking about it, it would not be too difficult to hand tack a piece of open mesh to the leech of a jib panel and the luff of the main and see and photograph how it set. I would do it to the second panel up as the bottom one suffers from a degree of vertical flow as the air escapes round the bottom.)

Call me lazy and I won't disagree, 

Cheers, Slieve.