My process for flaking down the head sail is to keep the sail hanked on, set up a proper flakes along the luff, then starting from the head, fold each flake back to the leech. Once it's flaked down, then fold it up from the clew a few folds, release the hanks, then finish folding towards the luff.
I have a 100%, so not sure if this technique scales up to a 135. I sure could have used a nice new 135 this past weekend! John 5956 Cool Change

