Anonymous wrote:Our preferred method would have been narrow webbing with one side sewn hook and the other loop (good quality), long enough for a couple rounds of self-adhering overlap. This would have been very easy to adjust!

One thing I should mention... we were building remote so had to make do with lashings (using a tarred nylon seine twine).

Our preferred method would have been narrow webbing with one side sewn hook and the other loop (good quality), long enough for a couple rounds of self-adhering overlap. This would have been very easy to adjust!

The lashings weren't too bad and cheap, but tedious to adjust.

Dave Z

Here are a few shots of our prototype main, Thai style lashings sized to induce 8% camber. Unfortunately, we didn't seem to take any after final adjustments. Sigh.

So imagine nice, smooth setting panels.

The upper, 'crab claw' panels are flat cut (idea was to act more like headboards, reducing any need to top up the lug). The deep hollows help move the CE inboard, reducing weather helm, especially when deep reefed in heavy winds.

Continuous, aft sheeting on main and mizzen at 6 and 5 parts, respectively. Each pair of battens is connected by a simple span (sheetlet), and the lowest part of the mizzen sheet is run forward along the boom to its tabernacle. Will eventually rework main sheeting to reduce twist.

Sail position is controlled by standing batten and yard parrels.

Downhauls are temporary, only being clipped to batten parrels in heavy weather.

The SJR main points higher than the mizzen, so can be eased to a close reach when the mizzen is closed hauled (angle diff can be seen in first pic).

I'll write all this up, sometime this winter. Hopefully, next summer, we'll be able to compare solid sails to Thai lashed, cambered sails (which may apply to a lesser degree with 'hinged' sails).

Dave Z

Anonymous wrote:

Dave,

With a flat sail it is difficult to see and feel the lift, I found the leach telltales very useful.

Bonjour

In experimentation leach telltales are not sufficent as they don't show the airflow around the sail or wing profile/camber.

It is more efficient, in particular to compare different cambers to incorporate telltales all along the sail profiles. When the airflow is laminar the telltales are parallel to the airflow. When the airflow is turbulent the telltales are falling.

Eric

Anonymous wrote:

Dave,
One thing I noticed when I hoisted my first cambered panel sail in 1994, was that the luff and leech no longer would flutter, the way they sometimes did on the flat sail. If that is a problem in your flat mizzen, I suggest you stitch on a low-stretch boltrope. If you stitch it on a bit taut, you will introduce a very light camber, and the weights will mostly move out to luff and leech, and keep these quiet.

Arne

We haven't noticed flutter on the flat cut sails, at least unless we're totally spacing out and pinched up WAY too high (by our normal standards), but thanks, and I'll keep that in mind.

Having read several accounts of flat cut performance, I get the impression that we sail further off and allow (encourage) more twist than most. So it's the uppermost panels that luff first, and then, for us, it's an overdue sign that we're pinching.

I somehow ran across Mr. Reddish's theory of twist + canted battens years ago. When we got around to JR, I remember thinking that PJR's emphasis on anti-twist might lower the flat cut sails chances of decent performance.

Now, having sailed them for years, I think it true. Our flat sail performance was good enough that, given its no-brainer ease of layout and construction, it took us a good while to make the leap to camber. Having access to a bigger, indoor space (caretaking every other winter) has lifted us over the bar.

Dave Z

BTW, we have never gotten around to adding telltales... something I REALLY need to do, and sooner rather than later. So everything I write on this is more subjective than need be.