I always thought that the floppy leech was to accommodate for the mast bending away when the sail loads up on the water under wind pressure. You can test this quickly while rigging by asking someone to stand on the mast foot of a rigged sail (with boom attached) when you push down the tip of the mast. The mast will then bend nicely and approximate a shape under wind load. The more the mast will bend, the more loose the leech needs to be in order to maintain a smooth sail shape under load.

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mr love said..
For the twist non believers you may want to read about why Nasa have spent 30 years studying Prantl lift distribution theory and developed a flying wing using the principle......LOTS of wing twist....result...way less induced drag and better stability.

www.nasa.gov/centers/armstrong/news/FactSheets/FS-106-AFRC.html

twist is not the same as flappy

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sheddweller said..

mr love said..
For the twist non believers you may want to read about why Nasa have spent 30 years studying Prantl lift distribution theory and developed a flying wing using the principle......LOTS of wing twist....result...way less induced drag and better stability.

www.nasa.gov/centers/armstrong/news/FactSheets/FS-106-AFRC.html

twist is not the same as flappy

and flappy is not the same of patchy
therefore twist is a solid color