By all means, first try fully inflating the sail, and adjust attachments points etc.

But my feeling is not optimistic. If nothing works, then ...

some food for thought

Upside down jib causes crease on the other diagonal.

So I don't think it's upside down jibs.

Also, in this case all jibs have the same problem.

My brain is not good at this. You could try flipping the entire set of jibs, as you did with the mains. Somehow I don't think that will be it, but my brain won't let me do it so I'm not sure.

The battens are fixed at 10 degrees as per the mains, and that looks correct. But the jibs don't seem to want to match that angle.

 It almost looks as though you have given the jibs a batten rise of greater than 10 degrees (as opposed to the upside down scenario which is equivalet to -10 degrees). 

But sheeting angle, and the application of scale factor for 45 degree angle are embedded in the procedure too, so I don't know what you have done.

I suspect a lofting error or assembly error across all jibs, but it's hard to tell without seeing the paper patterns laid flat, and calculations checked,

In particular, check  batten rise, sheeting angle and calculation procedure.

The diagram below assumes batten rise of 10 degrees and sheeting angle of 8 degrees.

Comparisons with cloth not much use, need to look at the paper patterns laid out flat.

Are top panel, bottom panel and centre panel are all lofted correctly?

If the answer is "yes" then look for systematic error in assembly.

I find it hard to visualise. 

The centre (blue) panel seems to be forced into a batten rise which it doesn't want to match.

Assembly error or lofting error?

I wondered if the centre panels are all upside down, (or top and bottom shelfs the wrong way round) but that too would explain a crease in the wrong diagonal. (I think... ?)

To me, it's almost as if you lofted the jibs with a 15 or 20 degree batten rise and forcing them into a 10 degree rise. That would explain the reverse diagonal crease. But there is also the complication of sheeting angle, and application of scale factor for the 45 degree angle and it's all too hard to guess.

If a simple explanation does not emerge, you will need to go carefully again through the lofting and check carefully for a fundamental mistake, and if it were me I would contemplate making a new set of paper patterns and a new jib. You might have to make a new set of jibs - not such a big task. Sorry to sound negative. My ability to visualise is poor and I hope I am wrong.

(My ability to visualise in 3 dimensions is so poor that when I made my jibs I had to make a plywood model before I was able to understand Slieve's lofting instructions. I found the instructions to be correct, but they did not lead me to understanding. Following instructions without understanding is an anethema to me, which is why I had to make a plywood model. So, I could be wrong in all of the above, but my gut feeling is you have made a systematic lofting error).

I must say, I struggled at first when lofting the jib panels (in fact I made a plywood model in the end, as I am not good at drafting in 3 dimensions) and I am wondering if you have lofted these jibs correctly.

Can you state the sheeting angle and the batten rise angle that you used?

Do you still have the paper patterns you made (of the centre panel, the top shelf and the bottom shelf) and if so, can you check the lofting procedure?

It’s great you were able to just flip the set of main panels in one piece, and not have to unstitch and re-stitch individual panels.

I don’t think your sheeting should mess with the drape of the sail. From the photos, it appears you are using the spanned running parrel downhauls, and if they are positioned and fixed correctly on the battens, when they are tensioned up a little they should pull the main luff up to the mast, and both luffs will be nice and straight. 

I found it necessary to fool around a little with the positioning of these parrel downhauls, adjust (and then fix) their positions to get a good setting sail. After that, they should keep the luffs nice and straight and the sail positioned exactly where you want it in relation to the mast. It doesn't take much to overcome the aft-seeking pull of the sheets.

((I think my jib luff is very slightly shorter than the main luff - or maybe exactly equal - certainly not longer - so when the main luff is tensioned a little, the jib luff necessarily carries a little tension as well. Nothing like the tension you would put on the luff of a bermudan sail, or a western lug sail - just enough to ensure they are straight, and the main luff is alongside the mast).

While I was finding the best position for the halyard sling point, and getting the parrel downhauls exactly where they work best, I too found it necessary to add a running yard parrel, but later, when the rig was tuned, I found I didn’t need it any more. Now I just have a standing parrel for the yard, just to stop the yard  flying too far away from the mast.

I keep a little tension on the parrel downhauls, and after reefing or shaking out a reef, they need to be adjusted again. I just have a couple of cam cleats for that. I found it necessary to have a downhaul on the boom also, but it was suffiicient for that to be just a standing downhaul – it takes up a bit of tension against the halyard when the sail is fully hoisted. It does nothing at any other time, so no need for it to be adjustable.

One trick I discovered by accident, is to find a way to arrange those parrel downhauls so they can’t run out very far, even when the control end is cast off from the cam cleat. They can be constrained so that they just slack off enough to allow the battens to go up and down. How you do that depends of your way of setting them up so I can’t explain how you should do it, but you can have these running parrel downhauls set up in such a way that even when they are completely slack at the control end, they never let the battens stray too far away from the mast.  In that case, adjusting them just needs a quick tweak to smooth out any creases, and there is no urgency about doing it.

Once set up, it seems to me after that to be a very pleasant and easy rig to manage.

keep junking !

Hi  !

I think somebody suggested mainlets before. And I think he was right then. If we tighten (now) the halyard to a 10(5?)-degree batten angle (rise), the pleats on the jiblets will decrease and the pleats on the mainlets will increase. Ergo, I'd try turning the mainlets upside down.

Regards - Jan