Hi Kurt,
Thanks for your input. I thought about using Top Gun for my new sail and perhaps should have contacted you to discuss it, because I like the idea of not using sailcovers, at least not unless the boat is laid up for a week or two in a sheltered spot, but I was leery after my recent experience with Odyssey, so instructed my sailmaker to use 7oz Dacron, which I will religiously keep covered when not in use. My bermudian Dacron sails lasted 12 years before beginning to show signs of deterioration and I still got another three years out of them before patching. The sailcovers were on about 50-60% of the time, I hazard a guess. The new sail is traditionally built, with triple-stitched, vertical seams.
I understand the need to have storm sails flat-cut, and my top three panels are a lot flatter than a bermudian-headed trysail and storm jib would be. There is just 20mm of round in the seams of each panel, with 50mm in the head of the sail, to allow for possible bend in the yard, not that I've seen any so far. The theory (we'll see how it works out), is that this will give the sail extra lift in light airs. My observations, after sailing with many different rigs, is that the top panels of a junk sail do more than their share of the work to windward, rather like the topsail of a gaffer or the square-topped racing mainsails in use today. I am adding to this effect (I hope) by having a shorter yard and leaving the top three, fan-shaped panels unsheeted. The leach of the top panel is almost horizontal, allowing the top two battens to fall out and add significant camber when the sail is fully hoisted. Once I am down to the last three panels, this effect will be reduced. I also have a webbing loop on the lower of the unsheeted battens, so allow me to incorporate it into the sheeting system if required.
I currently have my spare sail rigged, a small, flat-cut, Reddish-style sail, with a bonnet at the bottom to increase the sail area to about 80% of the optimum area. In flat water, it allows Arion to ghost along adequately in very light airs, and even tack, albeit slowly. Yesterday, in 10 knots of wind, I was sailing to windward with the windvane set at 45 degrees and tacking smartly. I emphasize this is in absolutely flat water. Once I get into the ocean, especially if there is an inshore chop, the game changes. But then Arion always struggled in those conditions, even with the bermudian rig. There is only so much you can expect from a 24ft, 5 ton boat with 10ft beam! Arion is a downwind warrior. With the wind anywhere from just forward of the beam to a dead run, we often sit on theoretical maximum hull speed, even exceeding it briefly on the crests of waves. If I really have to go to windward in coastal waters, I motorsail.
I'm fighting another battle with my health at the moment, and am unsure if or when I'll get back to sea, but I wanted to build a sail that I would be confident in on the longest offshore passages in remote areas of the South Pacific. My cambered sail performed magnificently and I liked it, but one has to weigh up the cost/benefit analysis. For regular inshore sailing, I'd choose a cambered sail, but I share Kurt's opinion that a flat-cut sail spreads the loads better, and is more reliable for offshore sailing. When you are a thousand miles from land, your hull, deck, rudder and rig need to be beyond doubt, barring misadventure. It might take a bit longer to tack into port when you reach your destination (I remember watching Zebedee tacking into Trinity Inlet in Cairns with her flat-cut sails in 2009), but the majority of your sailing will be with the sheets eased.
PS: I do believe it is possible to build a cambered sail that is strong enough for offshore work. After all, other types of offshore sails are cambered. But it is arguably a less important criterion offshore, and I wanted to get back to the simplicity and minimal stress that a traditional, flat-cut junk sail offers.