I've heard that an "expert" is someone who thinks they know more than everybody else. On that criteria, I probably am an "expert" sometimes.  But on the more normal criteria nope.  

But thanks to this site and its very helpful and knowledgeable and patient members, I do know a bit more about sail aerodynamics and construction and a lot more about sewing and have now managed to finish sewing the sail, but I definitely ain't no "expert".   

I've laid it out on the ground with the battens installed and on top of the mast and it looks alright if you don't look too closely at the stitching. 

 Next step is to match the 5 metre Al. tubing to my steel tabernacle and then match that to the dinghy,  Make the dinghy seaworthy, (it was neglected and bashed about for  a long time) and go sailing!!!

I won't be bold enough to dare say exactly when, other than sometime this year, hopefully :).

Dave

Slieve, at last I understand. Thanks for a very comprehensive answer including why you do it that way. This is the type of knowledge that I lack. Will keep you posted on how it goes and put up some pics in my album along the way. Slieve and Arne, many thanks.

Thanks Slieve and Arne for your replies. 

Arne, when I asked about leaving the luff rope loose between the battens, I meant unsewed except right at the batten, but trapped underneath the hem/tabling.  My thoughts were that I should tighten the luff rope slightly before sewing, then sew a very short portion of the luff rope on either side of the battens but leave the rest in the middle unsewed, but slightly tensioned.  Theory being that that most of the sail material would be free to pivot about the luff rope trapped within the hem, but with the tensile load being taken up by the luff rope.  A small luff rope rather than webbing because although the webbing will be a bit more aerodynamic lengthways, because of its depth it will be a bit more rigid and  restrict movement of the very front of the of luff.  In reality, it probaly will make no difference as with my first sail build, it's likely to be not the most perfect anyway, with my sewing abilities.

Slieve, like Scott, I'm not 100% sure what you mean about the tabling. 

If I understand you correctly, at the jib panel leech, if I manage to orientate the weft to run perpendicular to the leech, then a simple rectangular tabling should give me extra strength there as, essentially, the warp and weft of the tabling will be orientated in line with the sail's weft and warp and increase the strength of the leech.      

At the luff of the jib panel.  the weft will then be hitting the luff at an angle and so the additional tabling will need to be shaped like an extended Vee , ">>>>>>>>>", (I must learn how to put up a drawing) to bring the weft and warp of the tabling into line with the sail material. The point of the "Vee" representing the fold point of the tabling.

On your batten pocket construction, do you mean that you leave an allowance of half the circumference length of the batten on the joined lense shapes and then sew on a patch equal to half the circumference of the batten, allowing the batten to fit in between the patch and the sail, using the sail itself as half of the pocket.

As I know you like to minimize work, I wonder what you think of this idea.  When I was messing about last night with my practice sail, I thought to discard the seam between the lower shelf foot on one panel and the upper shelf foot on the panel below that and just join the two templates together.  I then cut out a complete lense panel with upper and lower lenses combined from one piece of material.  This would eliminate the need to join sew the two lense panels together along the batten line and means one less seam to sew on each panel. 

What do you think? or have you already tried it.  You still have to draw out each lense shape template individually before sticking them together to do the cutting, but it eliminates the need for 6-7 seams, each of which could go badly wrong, in my case anyway.  

Thanks again for your replies.  Dave

Hi Dave, You've raised some good points here, and I'll try and answer them in the order you asked.

On Poppy's rig I didn't use any of the A,B,C methods and spent (wasted) some time experimenting with different techniques. In practice nothing is carved in stone and you can get away with a lot. We tried an experiment with Amiina's first rig and put a simple hem along the batten line (similar to method A, and used cable ties through holes to lace the sail to the battens. It worked, but Edward, who did all the work , didn't want to see another sail tie for a long time. It wasn't a convenient method when it came to adjustments or sail changes. On the latest Amiina rig we decided to align the sail with the centre line of the battens, neither on the inside or outside, so that the jibs and main panels were in the same line (for some sheetlet experiments we wanted to try). This was easy to make as I simply joined the panels as for method A and then simply sewed a batten pocket (with gaps) flat on top of the join. I used a line of straight stitching nearest the batten and a line of zig-zag just outside it, above and below. The height of the pocket was arranged to be a snug fit on the batten. The raw edges at the gaps in the batten pocket cloths were simply turned in under and stuck with basting tape before sewing them to the sail.

I would be happy to use that again, particularly when working with angled shelf-foot panels as the pockets can be sewn onto the lenses before the panels are assembled. Putting the sail on the centre line of the battens works well with the split rig as the luff on the mail panels is in line with the mast and the sail should not get trapped between battens and mast when lowered.

Regarding question 1 and tabling, I'm sorry my comments have caused confusion. I have always tried to use conventional sailmaking techniques as used for Bermudan rigs as they have had a lot of practice in developing them. For example, I always lay my material with the thread line (either warp or weft) along the leech of a panel where the tensions will be high and where we don't want stretch. This encourages me to use vertical cloths which also tends to give minimum wastage of material. I then accept that the thread line at the luff is may not be in line with the luff on a tapered panel which does not matter for stretch as the bolt rope inside the tabling (Hem) takes the tension and hopefully the luff of the sail will rotate about the bolt rope from tack to tack.

My reference to the edges of the tabling not being parallel to the thread line of the material goes back to the destruction test I did on Poppy's jibs, by letting them flog for about an hour and a half when motoring into a force 6. A normal Bermudan jib would have been beyond repair after that, but only one split jib was damaged and I could have continued using the rig without repair. In practice the repair was a simple piece of sail material folded over the leech and a few lines of sewing. That convinced me that what I saw as a possible weakness in the split junk rig was nothing to worry about, and reckoned on simply putting tabling with angled edges over the leeches of the jib. Where the original tabling was a parallel strip of sailcloth with the thread line running straight down the fold line I now reckon that a parallelogram shaped piece of material still folded down the thread line would result in the edges being at an angle to the threadline and the edge stresses would be supported by both warp and weft threads. This is for the leech, and in particular, for the centre cloth of the jibs. Does this make sense?

As mentioned above, I want the luff of the jibs, in particular to be loose and to swivel around the bolt rope from tack to tack.

The luff bolt rope should be pre stretched at least, and I think on Amiina's latest rig I used Spectra at about 3 to 4mm diameter (if I remember correctly).

Arne was happy with the batten pockets being slack, but as the split rig uses downhauls I made the pockets a fairly tight fit on the battens so that they could slide in with no slack.

I know my original explanations of the rig construction are not very good. With each step I was experimenting so at the end of the day I had no single set method to report. Even the latest rig had plenty of variety, and I might even have difficulty in reproducing it. Why take the easy way when you can make it difficult? I haven't been trying to make a commercial rig, but have simply been trying to amuse myself and prove a theory.

I hope this helps, but if not try again, as I do.

Cheers, Slieve.

PS.1. I intend to add to 'Sheeting Angle and Slot Width thread in the next couple of days.

PS.2. I've been able to see a draft of an article on Amiina by David Harding for PBO as it went to the type setters, or whatever they are called these days, so hopefully the junk rig will get a little more publicity very soon.

Hello again, hope everyone is keeping well.  

Since my last post, I've been practicing a bit more with the various methods of panel joining as suggested by Arne and have decided that although it is more work than Method A or B, that I will go with Method C "The Sailmaker's Way". 

 I have made up small sample pieces for each method, joined them and fitted a batten pocket and find that Method C gives a smoother transition from tack to tack than the other two. I am also going to sew in an extra strip into the batten pocket between the batten and the panel seam to protect the panel seam from abrasion by the batten as per a suggestion made, I think, by David Tyler in another thread about sail construction.  

I have another few questions I'd like to get an answer to first though, if possible, before I start putting the real thing together.

1.   Slieve suggested he uses a luff rope with tabling on the jib panel luff and added this info into his answer

Quote "I prefer simple tabling, but with the edges not parallel with the thread line of the material. I always place the thread line parallel to the leech as in normal sail-makers practice".

I'm not sure what's meant by "the tabling edges not parallel with the thread line of the material".  Is this on the luff?  

In normal sail-making practice, as I understand it, it is standard practice for the sail material to be oriented so the weave of the material is perpendicular to the leech, in order to minimize the distortion of the material at the leech and help give an even airflow off same.  With the angle of the batten rise, this means that the luff-line can't then be perpendicular to the weave-line of the material.  and so, although the luff tabling edge will be parallel to the luff-line, the thread-line will not be.

Is this what Slieve means? 

2.  I'm also not sure about how much of the luff rope I should sew to the sail. 

Should I only sew a small portion above and below each batten leaving a portion of the luff rope un-sewn in the middle of each panel luff to allow the luff sail material itself to tighten to a certain degree when tensioning the sail or sew the luff rope the whole way along the luff, without any slack, but not taut so the rope will stretch along with the sail material and ultimately take the load. 

3.  What would be the most suitable type of rope for a luff rope? 

4.  When making the batten pockets, how tight should they be when the batten is installed?  A tight sliding fit or a light sliding fit?    

Sorry about what are probably basic questions for the more experienced sailors and sail-makers on this forum.  I've been reading up on the subject but you just can't beat real world experience for real world answers.  

Thanks for any replies. 

Dave.