yeah, I'm still trying to figure out that luff/mast overlay thing you describe... hard to get my head around what the theory is there.
Are we setting the diamonds to match the luff curve of the sail with no downhaul, right? So that diamond tension setting would represent the minimum tension (light air setting)?
I'm no expert (basically the opposite), but No.
If the mast is straighter than the luff curve of the sail, applying downhaul and mainsheet will bring the mast more in line with the luff curve, and the sail will get flatter and flatter, approaching only having as much pocket as is sewn into it.
When the mast is straighter than the sail it puts a little more belly and power into the sail.
If it's curved more than the sail's luff, I think you'd blow out the leech...but maybe that would just depower more.
There's also the issue of less rotation with more bend..
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Rick White's book has quite a few chapters at the end that are basically written by a few different pros, most of which discuss their telltale placement.
I agree w/ Jake, the 5.5 (and other boomless rigs I assume) doesn't like so much tension that mast rotation gets any resistance.
