It looks to me as though the joint I can see is too far forward. Just considering the forward section of the batten, there needs to be almost twice as much aft of the mast centreline as forward of it, for reliable articulation with no 'S' bending. Thus, if the mast is at 10%  of the chord, the joint should be at a minimum of 25% of the chord. There can then be a second joint at 50% of the chord.

With these proportions, I still think that downhauls attached to the battens near the mast centreline will be necessary.

Raking the foremast forward will help to keep the foresail asleep.  However, because the rig works so well downwind, you will probably maintain a good speed with only the mainsail once the wind reaches F3.

I've never used downhauls for reefing, myself, but you might want to give them a try.  Junk rig rarely looks very tidy!

Mast lift: as in topping lift.  It doesn't lift the boom, but it supports the sail at the mast, hence mast lift.

Hi David, thanks for the response. I was getting frustrated there for a while. Take your point about goosewinging, will work on that next time. Re windward...as I recal the battens where held snug to mast with batten parrels, but not a pretty shape. I took a couple of pics I will get uploaded to show the mess. something occured to me tonight. The original sails(Quay) and presumably cut flat. However joints have been added at some later? stage. Long batten parrels span this joint. Pics are "stuck" on my phone right now but will get them on here when I find a 6yr old child! Meanwhile thanks again. Paul     Update. I found this pic taken some time ago from a boat I was sailing. It happens to show a similar shape in foresail. At least now I know it,s repeatable and was not a one off. Or my imagination.

Finally managed to blag a sail on JR Trident Challenger which was factory built as schooner?JR in the mid 70s I guess. Original HM sails, owner limited experience. Mine zero with junk but 40 yrs/100,000mls on bermudian. Day 1...flat sea F2-4 broadreach/dead run,fair tide sog 6.5k,sunshine. Too good to last. On the +side I noticed the main had non of the bermudian tendacy to slat about so no need for preventer. Uncommonly quiet and stress free. 20 miles later we tried to run goosewinged and 1st issue arose. Could not get foresail to gybe over until we ran uncomfortably by the lee. Then it went but was not stable and gybed back into the shadow of the main.  but by sheeting in the main and deflecting some breeze onto the foresail managed to get it across but on releasing the main the "jib" came back to its original position. Not a deal breaker but something not right to my mind. Solution?

Day 2. the return was upwind with a foul tide F4-5 but reasonably sheltered closer inshore, maybe 1-1.5m waves. I knew it was too good to last. Began with full foresail and 1 panel reefed in main. Close very close/reach, 20% heel max. All going well SOG 5-5.5k . but then...I commented on the amount of foremast mast bend , which looked alarming to me. Possibly 1- 1.5 m. This initiated a little discussion and we decided a reef in the foresail would be prudent. I wanted to repeat the JR sailing again and not be helping fill out insurance claims with boat on the hard and the owners season finished. this led to an hours frustration trying to get the boat sailing efficiently again. SOG down to 3-4k, sea state same, wind gusting 20+k, boat comfortable but soul destroying performance. Now as mentioned we are both novices with this rig so here,s where we need help. Dropped the reef in staysail and re hoisted, sheeted in and the luff  was like a bag of washing. The new lower panel had so much bag it was turning the luff inside out, effectively blowing us sideways and backwards. After some string pulling my pointy sail knowledge decided we needed to get the luff straighter/tighter and more halyard tension was just raising the reefed batten off the boom creating more drag. Time  to bite the bullet and get wet. Lashed the batten to boom,ground up halyard and away we went. Not exactly steaming along but we looked a lot more respectable. Managed 4k SOG and travelled the 25miles in 6hours. No pressure on the day but on another tide we would have had to motor to get to our drying entrance in time. Solution ? Tinking about it I can't understand how an unsecured batten/panel can stay on the boom when when you re hoist after reefing. yes the leach id restrained by the sheets but what is supposed to stop the reefed panel and batten from simply rising again and allowing the luff to fall away to leward. The battens are jointed,alluminium. the sail seems to be an irregular fan with fairly wide panels, yard and upper luff parrels. no downhauls,fixed mast lift (Why not boom lift?) Someone point us in the right direction please, can,t leave this itch alone.