Another example. For a while I had the wrong prebend in my mast. Even at 20 knots double trapezing was tentative with 150 kg crewweight (different crew then now). I was lacking in all out speed so I started fiddling about with spreader rake and diamond wire tension. Now I got an rather good setting and I'm double trapping at 10 to 12 knots, pointing higher and going alot faster. So by adjusting the tuning of the mast you can achieve such great differences. Now If I suddenly start sailing at 130 kg I can do the adjustment in reverse.