To de-power and stabilize the spinnaker in extreme conditions

The Outgrabber in use:

  The out-grabber has two advantages:  on a run, it stabilizes the spinnaker; on a reach, it opens the leech to decrease heeling moment, as in the photo above.
Spinnaker Aids
  To increase your control and therefore enjoyment of your spinnaker,  consider a Spinnaker Shop spinnaker net on long passages.                       
For short-handed racing or cruising, a spinnaker sock is invaluable.