Here's a great way to remove the Derlin screw, without risking damage to the threads.
Get the biggest, longest screwdriver you can find that will fit in the screw head.
Heat the screwdriver until it is very, very, very hot (such as, put the tip of the screwdriver in the flame of a BBQ grill for a few minutes).
When it's hot enough, immediately put it into the screw and push it in as the Derlin melts. Make sure it goes into the screw at least 1/2 inch. DO NOT turn the screwdriver while doing this.
After you've made this new slot in the screw, remove the screwdriver. Pour cold water over the screw so the plastic hardens. Place the screwdriver into some cold water (such as in a cooler with ice).
When the screw and screwdriver are sufficiently cold, insert the screwdriver and remove the screw. If the screw is really stuck, it helps to use a pair of vice grips on the shaft of the screwdriver to add leverage when turning.
The beauty of this method is, you don't destroy the screw (it can be re-used) OR the threads, and everything you need can be found on the beach at a typical Hobie event!