Just go back to Quoddy's question ...
He asks why all these prominent _larger_ boats are moving away from travelers. I gave an answer (Roger actually provided the original reason if anybody would care to remember). All of the 'experts' have not come up with anything yet ... Don, I'm listening ...

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Todd gives a good, valid reason.
FourPoints, I understand your answer and it makes sense for boats the size of ours. I question if the models that Quoddy is talking about have large hydraulic rigid vangs, which would be more powerful than the kind that we could install on our boats.
For the record, I have a traveler, I know how it is used, and I modified it last year (following our earlier discussion) so that I have line control rather than pin-stops so that I can use it more effectively. I also have a boom vang, but it is the soft variety. So I understand completely how the traveler, mainsheet and vang interplay.
Going back to Don ... I can tell that you know how the strings are pulled to create the sail shape and angle of attack that you desire. What baffles me is that you do not seem to have any understanding or concept of the mechanics involved. All your 'concepts' are based on having ropes to pull the sail into position.
Do you understand how a modern hydraulic vang works these days? When new mechanics are introduced, some of the old rules are going to get tossed out. You obviously don't understand my point that when a rigid vang has the ability to fix the vertical angle of the boom, the mainsheet no longer works as an integrated system with the vang.
FourPoints may be right, in that even the large hydraulic vangs don't have that power. I don't know that answer and would welcome a response because I openly admit that my argument is predicated on that assumption.
Also, I know that you write that draft_position_ is affected by the mainsheet. But you don't mention draft depth. When we had these discussions before, RichH definitely said that draft depth is increased when the mainsheet is eased and he used that argument to base his position that a sail is powered-up when easing the sheet (therefore it is better to ease the traveler in a gust). This came out when some of us were refuting the position that twisting-off the main increases power. As we all should know, increasing draft depth (in a windy condition) typically increases power. Many of us were agreeing that twisting-off the top of the sail reduced power. Rich was implying that the increased power from draft overrides the reduction from twisting off, particularly because of the pendulum effect of the top of the mast in a heavy seaway.
I asked you for your position on this but you did not reply ... I'm still waiting. I would appreciate it if you didn't go thru your ABC's everytime these discussions come up and opened your mind to demonstrate some knowledge instead. If that sounds harsh ... so be it. I don't like being treated like a fool.