Agreed! And I would be willing to bet that your boat does not have a loose footed main. Nor,I am certain, do you have end boom sheeting. If you did, you would find a vang to be very ineffective to windward. However, that was not my original point. These threads tend to drift from the original posters question, as do boat rigs, one size answer does not fit all rigs. However control line size does. The larger the line the greater the control power over the sail shape. After watching a guy put a vang line on a deck winch and proceeding to rip the vang out of the boom, I kinda got the idea that he wasn't too sure of the limitations of a vang to control sail shape. After watching a guy rip the boltrope footed main out of the boom with the mainsheet, I kinda got the idea he didn't know when to reef. Reef early, reef often, the reefed boats are usually not the ones out of control or with broken rigs. Not to totally subvert this thread, but if you have a footed main, mid boom sheeting and the outhaul, halyard and cunningham are all tight, by all means, snug that vang, if it wasn't already, if that doesn't do it, it might be time to reef. Just MHO.