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.