In reply to Kevin: There is also the Welsford Pathfinder dinghy Cirrus which is featured as Boat of the Month here (scroll down to March 2023) which features a SJR similar to (but not identical to) the Amiina rig.

Jan might note that it is a 4-panel sail. It also has a proportionally larger upper panel. However, I would suggest to Jan, for a first sail, to follow exactly the proportions of the Amiina sail, leave off the bottom panel, and don't bother with the split in the top panel. That is, if he finally settles on a SJR.

Jan: I really liked the idea of extending the swinging boards... With a new sail it may not be necessary. The current boards may be fine how they are - or (as in standard dinghy practice) it may be sufficient to adjust the angle of the swinging boards, with the lifting tackle. I would suggest leave that question for now...  don't change too many things at once.

The sail catcher can be convenient, also when transporting by car, because the entire sail with battens is packed like in a case and it is easier to keep order. But doesn't such a large surface cause too much wind resistance? Certainly I find mine convenient to keep everything packed together for transport. You can use "hook and loop" tape at the top. to enable the sail catcher to become a closed bag, ie a sail cover, if you want. I have no idea if it "causes wind resistance", I would suggest that if so, it is a minor detail. In fact it is tidy and in line with the sail and may well disturb the airflow less than the exposed panels of a conventionally reefed junk sail. (I look at it as a lower extension of the sail).

Spanned downhaul parrels… So a separate downhaul must be used for each panel? No, they are spanned, so that each one operates on two panels. You can refer to Slieve's notes. The relevant chapter is here.

On the 5-panel Amiina sail, two of them is all you need. The only proviso with the spans is that you need enough space between the boom and the "deck" for when the span is in the reefed position. Slightly more than half the width of a panel is sufficient. I believe this need not be a problem with your set-up, but take care not to have the boom too low, as you need to allow enough room for the spans to fully extend.

Also, provided you do not alter the proportions of the Amiina sail, you will find that no other control lines are necessary.

If you use a 4-panel version of the Amiina sail you might be able to have a standing "downhaul" and short standing batten parrel on the boom (ie fixed, not needing any adjustment) as you would anyway, and just a single spanned parrel downhaul for the two battens above the boom. Perhaps the top batten and the yard could each just have a standing short batten parrel. That would give you the ability to reef one panel, or two panels, and would reduce everything to just one control line. I haven't tried it though. I find two control lines not too difficult to manage. They are left free when you hoist and just need a tweak when hoisted, tweaked again if you reef. A couple of cam cleats is all you need.  (If you change the shape of the sail or the "planform" then you may need additional parrels or hauling lines, you will have to find that out for yourself. That is why I would stress, stick to the exact proportions of the Amiina sail.)

I would like to limit the number of lines as much as possible, as it can cause lines to become tangled in the trunk of the car and when preparing the boat for sailing. It's always a problem if you have to dismantle everything. I have my halyard, lifts and mainsheet block attached by quick release clips. (The halyard is unclipped from the yard and remains with the mast. The mainsheet block complete with mainsheet is laid neatly in the sail catcher, together with the sheetlets, nothing is un-roven). The parrel downhaul spans are also just clipped on to the actual downhaul ropes, so the parrels stay clipped onto the battens and go into the sail catcher, while the downhaul ropes ("control lines") stay with the boat. So the entire bundle (sitting tidily in the sail catcher complete with its downhaul spans, battens, sheetlets and mainsheet) are all stowed in the sail catcher free of tangles and ready to be re-deployed. The sail catcher is now a sail bag, with its bundle inside, with everything unclipped, and thus separated from the mast. For transport, it can be stowed in the boat or in the back of a car, without the risk of tangles. Clipping everything back on takes a little care, but it is still only a few minutes.

...soft rubber tubes in the place where the battens will rub against the mast...Metal battens on metal mast might need fendering, others can advise you on that.

I'm also wondering how you attach the sail to the battens. For a simple little sail I have found wooden battens (split, one half each side of the sail, and screwed together through the sail) to be a quick and easy way, which does not require batten pockets or fendering against the mast. That is what you see in the photo of my boat. If you are only making a polytarp sail I would certainly recommend it. (For a better sail - well, that's a matter of opinion. I am trying batten pockets and aluminium battens this time round - already finding that it creates a great deal more work and for a little dinghy sail I doubt if batten pockets, metal battens and fenders, and hoops and loops are worth the trouble. Others might disagree. For a dinghy I would go back to split spars made from wood and screwed together through the sail - preferably some nice straight-grained spruce, though I have had to make do with pinus radiata which is not as strong and a bit heavy, but it still works. Rigging a dinghy is a slightly different proposition to rigging a larger sailboat. Split timber battens are quick and easy to assemble with a cordless drill-driver, and also easy to dismantle if you ever need to. Not everyone will agree with doing it that way.

I just want to make a general comment. We are focusing here on many minor details and forgetting the big picture (one of my many faults). I think your first priority is to produce a scale drawing showing your proposed sail plan in relation to the lateral plane of the boat (with the boards in their normal position, and the rudder.) From analysing a photograph I felt that a 4-panel Amiina sail would fit your mast and probably bring the centre of area of the rig far enough forward to solve your problem and perhaps leave a little weather helm you could tune out with the centreboard.

It looked pretty good to me, but only based on a photograph and not yet confirmed. Now, when I see your "avatar' showing your proposed sail, it looks to be much further forward (and too tall) - but without the swinging boards in the picture it is impossible to be sure if it is too far forward or not. Without a proper scale drawing, who can say?  Who knows: you might be better off with a slightly lower balance sail than 33% - if you over-do it then you will have lee helm, putting you in a worse position than you were before.

So, before settling on the SJR and cutting cloth - and certainly before worrying about the minor details, make sure you have carefully considered the relationship of the centre of area of the proposed sail, in relation to the centre of area of the under-water profile of the hull (with the boards deployed in normal position) - preferably with a scale drawing. The centre of area of a Amiina sail will be near enough in the same vertical line as a vertical line through the midpoint of the boom.

The goal should not be to have a SJR - the goal should be to have a sail which has the right balance to suit your dinghy, with your fixed mast position (and current position of swinging boards).

[Edit: I scaled up your "avatar" drawing as it just doesn't look good to me. I noticed it is similar to, but different from Amiina's sail in a couple of respects.

That's up to you, although I am sure if you contact Slieve he would be helpful and willing for you to use his design. Of more concern: your proposed sail appears (by eyeball) to have much more balance than 33%. I think you definitely need to re-consider that.]

A quick search for laser on the Knowledgebase produces an article in JRA magazine which featured a SJR laser and wayfarer in Magazine 79

Jan: However, before Christmas there is some work to be done at home...

Your priorities are right!

I read about Tyvec that it makes noise. What is your opinion on this?

I used it on the bottom  panel, for a while, as an experiment. I don't recall it being noisy. It is very soft, I would have thought the opposite. 

As for the mast - I have already bought a second mast, 465 cm high from the bottom of the boat...

I think the old mast was tall enough, and four panels is enough for that little boat. Just my opinion.

 ...the same drawing is in my logo, but I don't know why it is not displayed in the post header...

It is displayed - have a look at the "Introduction" thread. It is there, but not very distinct. For some reason I don't understand, the photo that you put in the personal details section of your Profile is displayed in the post header of some forums (Introductory, for example) but not in others (the Technical forum, for example).

However, if you put a photo in the "Current Boat's photo" section of your personal details, in your Profile -that photo will appear in the post header of the Technical forum.

I'm also wondering how to plan the arrangement of sheets and sheetlets. 
Everyone seems to have their own favourite way of doing it. I sheet the top two battens with one sheet, and the bottom three battens with the other sheet, so I have two mainsheets. I didn't know any better. It worked well for me so I never changed it,  but most people don't seem to do it that way. Maybe someone else can give you better advice.

I noticed, that in “Serendipity” you have only one lazy-jack, or rather topping lift, is that enough?

Serendipity has a pair of lifts at the mast (one each side) and another pair of lifts  near the aft end of the lower batten (boom) (one each side) [but not so far aft that the yard can get on the wrong side of it]. As far as lifts are concerned, I think that is normal. The forward pair is sometimes called "the mast lift" and the aft pair sometimes called "topping lifts".

However, I don't have lazyjacks attached to the lifts, because I have a McGalliard-style sail catcher which does the job of muzzling the sail when it is lowered. This is not common, but for SJR it works better than lazyjacks, I find. You will find with SJR that the jibs don't seem to muzzle properly, they seem to escape the lazy jacks and flap around.  I found this annoying so I made a full sail catcher following Slieve's drawing, which cured the problem. The sail catcher has other advantages too, in my opinion, though only SJR rigged boats seem to use them. [It is possible that conventional batten parrels don't work conveniently with this sail catcher - that's the only reason I can think of why some people claim that this type of sail catcher doesn't work. This is speculation on my part. The system works extremely well with running parrel downhauls, I do know that].

Sail catcher designed by Slieve McGalliard. The front fitting on mine (a U-bend which joins the two skeletal tubes at the front) fell apart, as you can see  - it is not needed anyway.

I plan to use batten parrels in the form of tapes fastened with buckles

I think spanned running downhaul parrels are best for McGalliard SJR, very simple and they work very well for that type of sail. Mine unclip, to enable the bundle to be quickly removed from the mast if necessary.

Merry Christmas.

Jan: a few things to think about over Christmas.

Here is a scaled down Amiina Mk2 rig with the bottom panel missing. The sail works quite well with one reef in, so this should work.

It is not accurate, because this sort of thing is better done with a proper drawing.

This is enough to convince me that a SJR can fit on your mast, and bring the centre of area of the sail quite a long way forward, as shown. This is as far forward as you will get using a junk rig, on that mast position, and whether it is far enough forward I don't know. (Actually I made a mistake, it can go a little further forward - the vertical line drawn here at the mast should represent the mast centreline, so you can move it forward another one or two cm to coincide with the centreline of your current mast.)

If you want to go to the trouble of making a little SJR, then I think it could be made to work. It would improve the situation. My guess is, you will still have weather helm if the swinging boards are in the vertical down position.  I do not think you will get lee helm from the arrangement and should not need to make adjustments to the jibs, nor should you do that.

If the boat still has too much weather helm, there will be nothing more you can do to the sail. In that case I would put slightly longer blades on the swinging boards (they are not actually  dagger boards) and deploy them at an angle - I mean, swing them back a little, not vertical.

Like this (exaggerated). Adjust the angle until you get the right helm balance.

This means you can utilise all of the mechanical arrangements you currently have, with no major or structural alterations.

Other comments:

Maybe I'm wrong, but the SJR seems to be a more efficient sail and better balanced. I have already made a model of this sail (made of agrotextile, 1:5 scale), I can also send a photo.

Please do send a photo. I am not sure if the SJR is a more efficient sail, but it certainly does work well if the jib cambers are made accurately. At least, that is what I know of the Amiina Mk2 SJR.  That sail is a package, of more careful thought and design than its simple shape would suggest, and I would not attempt to design my own SJR, nor depart from the proportions of that sail.

"Better" balanced? The high balance will improve the situation on your boat with its mast in that position, and I personally prefer high balance (for other reasons), but not everyone will agree that high balance is "better" - lower balance junk sails are more usual.

Be warned: 33% is near to the limit of possible balance. If you make a mistake and end up with balance of higher than, perhaps 35%, you will have a failure. Yes, there is at least one recorded example where this happened, due to not calculating mast balance correctly. On a SJR ignore the slot when calculating balance. The mast centreline should divide the lower battens in the ratio 1:3 and 2:3 Then you will have close enough to 33% mast balance and will be safe.

Less than 30% mast balance for SJR makes no sense to me. I think if the balance is to be less than 30% a contiguous sail might be better. Other designers (such as Paul Th and Arne) have been pushing the balance of contiguous sails up towards 30% and can give better advice than I can about that. To make a SJR that will most benefit your situation, as well as to make the most rational use of the split rig, you need 33% balance. No more, no less. The battens must be rigid and the sail set firmly in position (which it will be with with the parrel-downhauls) - I have not experienced it, but I would not want the sail or its centre of effort  to move forward and the rig to become aerodynamically unstable.

I also started making cardboard templates on a 1:1 scale, and bought 6 aluminum tubes 12mm x 1mm x 2000mm each.

It sounds as though you are committed. Good luck.

I'm just wondering how to make batten pockets and batten parrels. It is possible that I will make test batten parrels from a ribbon/rope tied in a knot.

You can read Arne's notes in the technical documents archive on this website, for how to make batten pockets.

I would not use conventional batten parrels for the SJR. For that sail, I think it is better to use running parrel-downhauls as described by Slieve in his notes, in the technical documents archive.

I want to make the batten pockets in such a way that the jiblets can be easily cutted, and moved along the batten if it is necessary to reduce their length/surface. And to reduce the mast balance this way ? 

I wouldn't use this project as a platform for experimenting with SJR jibs. Just keep it simple, use the Amiina Mk2 planform which works. Just set the jibs up with a sheeting angle of 12 degrees and a designed camber of about 10%, The mains panels should have a little less camber - say 8%. (In reality, the measured camber of an inflated shelf foot panel will be a bit higher than the designed camber).

I'm still hesitating whether to simply make the first version using the origamii method and make appropriate eyelets on the edges of the batten pockets, which would make it possible to easily replace the panels with various other variants - with a different camber or made using a different method (shelves/barrels).

The origami method may well be suitable for this little project. It looks simple and easy. I have not seen it done so I don't know. You could contact Paul McKay. 

If you decide to make sewn-camber jibs (instead of origami) then they are best made using angled shelf foot method as described by Slieve, and for these little jibs I would recommend spend one day and make a "tailer's dummy" as a mould to build them on. I can explain later (or see below), this is just my own idea, not thought necessary by other people, but I found it to be the most practical way to make and then to replicate a relatively small shelf foot sail panel, with accuracy, from very light cloth. Also, once the mould is made, it makes it extremely easy to mark out, cut and assemble and baste together the components of a shelf foot panel, and will probably save time in the long run if you are making three identical panels.

(Use the lightest cloth you can  - the little jibs on a SJR sail the size we are talking about here are just pocket handkerchiefs. I looked at some rip-stop spinnaker nylon the other day, 48 gram/sqm looked enough for your small sail. I have also experimented with Tyvek - fabulously light for its strength, also  lovely and soft, and has potential if you want to experiment. I made a couple of panels with it as an experiment and was quite impressed, although I think better with lighter stitching than I was using - I couldn't seem to get the sewing machine tensioned right for it, it is so light - maybe the seams could be glued. It is certainly strong enough for a little junk sail. (junk sails generally are subject to considerably less stress than a conventional western lug sail). Tyvek may not withstand too much UV. I would regard Tyvek as experimental, not proven, but with real potential for a tiny junk sail.).

Make sure you mark the jibs top and bottom as you make them - if you don't, then it is easy to get a jib panel upside down when you assemble the sail. (Don't ask me how I know this).

The mains panels can be made with shelf foot or barrel method, whichever you find easiest.

If you use the Amiina Mk2 planform, don't split the top panel. The top panel can be made using barrel method if you want. It is usual to have less camber in the top panel, or probably even flat, if you you like. I think I gave mine about 5% - I don't recall exactly.

(The tailer's dummy is described in this article here. Other people will say it is a waste of time. For a tiny shelf foot sail panel which must be fairly accurate, and will be replicated. such as the jibs on a Amiina-type sail, I would say it will save you time and you will achieve 100%  accuracy. If they are not reasonably accurate, and very light weight, these tiny little jibs on a boat your size would be somewhat useless I would expect.

Also: do not increase the sail area shown here, unless you plan to use a taller mast. The mast height is important on this low yard-angle rig, and needs to be slightly taller than the highest point on the yard, as shown in the above diagram. Anyway, the above diagram looks to me as though the sail area is plenty, it looks like an increase on what you currently have. You don't want to over-canvas that little boat and the Amiina Mk2 sail is quite surprisingly powerful. If anything, I would make the sail a bit smaller than shown here, but you will know what best suits your little boat.)

That's pretty much all I can tell you, some of it is personal opinion, based on a certain amount of dinghy sailing, and very limited amount of experience building a sail - and quite a lot of experience at making mistakes in the process! Good luck. And Merry Christmas.

Edit I have pushed the Amiina Mk2 planform at tedious length but for good reasons. This sail reefs reliably, there are no issues with batten stagger,  vertical leech ensures sheetlet tangling does not occur, the long yard ensures it never gets wrong side of the mast or the lifts, it does not seem to be prone to "fan-ups", the sail can be dumped into the lazyjacks (or better still a McGalliard-style sail-catcher) without issues etc etc  - the stresses on the spars, sheeting forces etc are all very low, nothing other than the running parrel downhauls are needed to keep things in place - it is in fact a model of design harmony. Its brutal simplicity also means replicated sail panels rather than lofting each panel individually, so it is a relatively simple sail to make, as far as the SJR can be simple. I look upon these things through the eyes of a beginner (which I am) and doubt if you could improve on the design. It is a package of interdependent variables, the changing of any one of which, or its proportions, could undo that carefully balanced combination. Like the Johanna planform, it now has a proven track record as a modern cambered sail type that can be successfully made by an amateur sailmaker. The sail has its requirements and does not fit all situations - in fact, generally speaking it is possibly not the ideal planform for a dinghy - but I think it would fit nicely in your situation, albeit very much a miniature and requiring a bit of extra time in the making. 

Jan, you wrote: I'm also not sure if the "Introduction" topic is the right place for further discussions. Maybe this conversation should be moved to a more appropriate place?

As with most of the points you made in your recent "Introduction" post, you are right.

So, I have created a new thread. I would like to reply to your points, because it appears that you have already decided on a split junk rig (SJR), and there are some further comments I would like to make on that subject. However, I need a little time.

In the meantime, I put an edited version of your introductory post here, as other people may want to offer solutions other than a SJR. (I do not have a wide range of experience in junk rig and there are better advisors than me, so I leave this open for a while in case others would like to offer suggestions). 

Jan wrote (edited): I bought a small foldable rowing boat (2.5 m long), converted by the seller into a sailing dinghy. 

The dinghy (I called she "Tycia", which means "Tiny") - was produced in the former USSR as a foldable rowing boat (link).

 Her great advantage (unlike pontoons and other inflatable boats) is that she has a relatively stiff and light aluminum skeleton, making it easy to expand she [her] to a sailing version.

The sailing version (Bermuda sail, rudder and 2 daggerboards) fits into a passenger car when folded. 

The main disadvantage of the sailing version of the dinghy is that the place where the mast can be located is too close to the midships [too far aft], and the daggerboards are too close to the bow, [too far forward] which causes the dinghy to be very windward..[excessive weather helm, and often gets "into irons" when "going about" (tacking)]

Unfortunately the mast attachment point cannot be moved forward.

I realize that the daggerboards need to be moved closer to the stern, but for now I want to focus on the sail.

So I started preparing my first version of the "split-rig" sail.

I suggest first: post a drawing of your little boat, showing current rig, centreboard(s) and rudder - to scale if possible.

Regarding origame, sail, it might be a good way to try - I suggest you contact Paul McKay, via the membership Directory.

Regarding batten parrels for a SJR, I suggest you read Slieve's Chapter 11 here as his spanned, running, parrel-downhauls suit the SJR better than conventional parrels on his split junk rigs.

For a hybrid of Slieve's and Paul Mc's ideas, a decidedly different take on batten "parrels" (hard parrels), and a third type of high-balance split rig, you might have a look at the Boat of the Month gallery and scroll down to the boat featured in September 2023.

Altering the areas of the daggerboard(s) and rudder could change the position of the centre of underwater area - may help - if that is easier than making a new sail. Shifting the daggerboard(s) further aft would certainly do that.

However, if you want reefing, then a new sail will be necessary anyway, so you might as well start with that (as you have already concluded). I have had experience with the bermudan dinghy pocket sail also - nice and simple, but a dangerous rig for an elderly person (like me) in a dinghy which can  not easily recover from a capsize. You need instant reefing, together with the ability to instantly drop all sail, conveniently (tidily), if possible. Junk rig provides both.

I leave this now in case others have suggestions.

I will comment further on SJR (and also your side-by-side dagger boards) later when I have time (unless Slieve sees this and wants to reply).

Best of luck

PS one more thing to think about. To keep things as simple as possible, junk rig sheeting needs to be located aft of (further behind) the sail. If you want any sort of junk rig on your little boat you will probably need a "boomkin" or "bumpkin" - a spar extending back from the stern, as a sheeting attachment point further back than the stern of the boat. How long it needs to be depends a bit on the type of junk sail. It can be removeable, of course. From the photo it looks like you already have one, so you will know what I mean.