I recently prepared my Columbia 9.6 for a trip to Hawaii from the Puget Sound. As part of that preparation I decided to build (or have built) an 'offshore' suite of sails. That, of course, required significant research before I put Doyle to work making them. Doyle and I came up with a negative roached, battenless and no headboard main with a shortened leach as the preferred offshore sail for my particular vessel. Reasons:
1. No headboard = no headboard to get caught in shroud lines while trying to raise, strike or reef the sail off the wind.
2. No battens = simpler, also nothing to get caught in shroud lines.
3. Negative roach = reduced leach flutter compared to similar battenless main without negative roach.
4. Shortened (by 13") leach was my idea. I stand 6 feet, 2 inches in the cockpit. Even though I use a preventer, getting hit in the head by the boom during an accidental gybe was a safety concern. Shortening the leach ensured the boom clears my skull by several happy inches.
Here's what on-the-water testing revealed since:
1. It still ain't easy to hoist or strike the main off the wind. But it can be done and it doesn't get caught in the shroud lines.
2. There is some leach flutter. I expected this, but judicious use of the leach line pretty much eliminates it.
3. Reduced weather helm, especially when close hauled and approaching hull speed. The boat just plain balances better, to the point where I can keep the main driving well past the point where I normally would expect to be forced to 'feather' the more traditional, battened main that I normally use for Puget Sound cruising and club racing.
4. Flaking / tieing down the main onto the boom is simpler w/out having to worry about aligning the battens parallel to the boom.
5. Power loss? I didn't buy the battenless main so that I could ghost along in light air. I bought it for offshore, trade wind sailing. In similar conditions here in the Puget Sound I simply don't notice any difference in boat speed when the wind gets above 10 knots. Additionally, the helm is better balanced and the boat more comfortable. I'm sure that there would be a boat speed difference if I could do an on-the-spot simultaneous comparison, but I'm satisfied that the difference would be small. Heck, there's probably a point where not having to drag the rudder through the water sideways to counter weather helm makes the battenless main drive the boat faster.
6. A well-balanced helm makes my servo-pendulum self-steering system breathe easier too.
So, would I recommend a battenless main for offshore use? Generally yes, but I also will be quick to say it depends on both the boat and the crew. For an interesting discussion of such sails on ketches, check out main-sail