In heavy air, control of heel is paramount. More twist will help keep the boat upright. The boat will typically have to sail at wider angles (foot) to have the power necessary to blast through waves, and that will generate more heel. In smooth water, the helmsperson can "feather" more, or let the inside telltales lift in puffs. The overall sail shape will be as flat as possible, which will help induce twist and open the leech. The traveler, which is great for fine-tuning balance in moderate conditions, usually does not provide enough gross change to handle big puffs, so twisting the entire sail with the mainsheet works best. I typically pull the traveler up a couple of feet above the leeward coaming and play the sheet to control heel. In windy conditions, use the boom vang to help augment the mainsheet.