I learn't three important lessons on sailing in heavy weather at the ranking event at Keighley's Weecher reservoir.
Rig set up
When setting up the boat make sure that the jib leech does not open excessively in the gusts. You want an open leech but it needs to be controllable. Whilst you can set the leech tension on land it is best to put the boat on the water and see how the jib leech responds to the gusts. If it opens to much, I tighten the jib luff tension bowsie. Once I am happy with the jib leech I then check that the boat is balanced and will manage any adjustments by tightening or loosening the backstay. The jib luff and backstay movements are only a max of a few mm. All the other settings on the boat remained as for lighter conditions.
If the jib leech is too loose and the main leach tight relative to the jib leach, the boat will always try to head into wind making beating fast and tacking impossible
If you get the jib leech tension correct you will have no problems tacking in the gusts. All you have to do is get the boat through head to wind and the sails will do the rest because as soon as the jib starts to fill, the bow will blow away from the wind. At this point you ease the sails considerable to put the boat on a close reach to accelerate and once the foils have traction you can sheet in and the boat will steer itself.
The stronger gusts were such in the final race that if your sails were full the boat was flattened. We had two downwind legs which were just off a dead run so the trick was to sail as low as possible in the lulls and sometimes I went 30 degrees lower than the course, so when the big gust came in I could head up and let the sails flap if needed. This way I avoided the dreaded pitch pole and could progress at speed to the mark. While I was progressing to the mark with the sails flapping and the boat upright those behind where pitchpoling and making little progress.
At the end of the race, the successful B rigs were a long way ahead, but managing an A rig round the course in those conditions was extremely satifying. Of course if the waves were significant I would have changed down early as it would be impossible to tack an A rig.