Downwind we always talk about sailing at the optimum angle. In light air this means sailing higher to create apparent wind, and in moderate air sailing deeper angles to take advantage of the pressure. In heavy air there is only one narrow range you can sail in. I call it the survival angle. Sail to high and you will load up and round up to weather (a normal broach). Try to sail too low and the boat will want to bear away and round down, potentially all the way into the dreaded accidental jibe. Avoid this at all costs. To avoid broaching to weather, aggressively bear off as a puff hits. If you get too low and the boat starts to get too flat start heading up. Ideally, you should try to have the same amount of heel and load on the rudder pretty much all the time, working the boat hard within a narrow range to maintain similar pressure. Trimmers and the rest of the crew are equally involved with driving. Keep the weight aft. Ease both sails and hike in the puffs to help the driver bear off. Trim and move to leeward if you feel the boat getting too flat and too deep. Don’t ease the spinnaker and boat can’t bear off, over ease and it will roll to weather and try to round down into a jibe. With a symmetrical spinnaker, trim just before you feel the boat beginning to roll to weather to help dampen the oscillation, then ease before it rolls to leeward.