Nick wrote: "... with e.g. 66% main and 34% jib... "

That is a dangerous idea which might well result in an over-balanced split rig.

The balance of a split rig is NOT the ratio between jib and main sail areas.

The balance is the ratio of that part of the total sail outline (including the slot if any) which is ahead of the mast centreline - to the area of the total sail outline. As 34% is very close to the limit, you may already have an overbalanced rig with these numbers. Any inaccuracy could potentially worsen the situation. It has happened before.

The simple way (which is slightly inaccurate, but on the safe side) which can be applied to a normal sail outline shape, is to ensure that the mast crosses the lower battens at about the 33% point. (Or 34% if you want to push the boundary, but I wouldn't).

Devo as you could read in my previous post, I was wingling between the 4 mm outhoul starting at top or bottom.

I see you think we need the 4 mm to go down all the way to the cockpit.

But my idea was to connect the 4 mm at the top to the one line sheet which is already there. The sheet has already an automatic pull tension created by the wind force on the whole sail.

So the sheet pulls the 4 mm. My spreadsheet was only dealing with a linear power over all the blocks, which of course is not the truth. Part of the overall friction is less on the top for so to increase lower down. But there again the sail area is a bit bigger, maybe balancing out the differences.

The spreadsheet shows there is abundance of spare power to pull the camber flatter when the wind force increases. But now the trick. How much does the system have to pull each grommet to make the perfect camber for each wind force?

The bungees was also in my mind, but I am afraid we end up again with an approx. Maybe we should think about different friction for each grommet according the camber we want?

If the friction of the small blocks cause the sail to stay flat, then use a bungee to pull the opposite direction to get camber on the sail.

1. Uncleat 4mm line to let leech relax 

2. The bungee pulls the leech toward luff

3. The top most panel will get camber and slowly works its way down to the boom.

disclaimer: I haven't tried this yet. Some experiment must be done to figure out the friction per batten, the weight of the 4mm sheet, from yard to bottom cleating point, the pull force of each bungee, ... etc.

I am in the process of redoing all my sails to a luff pocket aerojunk rig (aka wing'soul). As all junks, its has superb reefing and twist management abilities. Add performance increases of the slot affect (from the mini-jibs), and the low turbulence of luff pocketing the mast... should be an outstanding rig. 

Hi Nic,

I would also be in doubt whether the friction could be overcome... However, there is no better way than to build and test it! ;-)

Cheers,

Paul

Hmm, forgot the Jib, which means that the tension on the sheet would be 25% less?