In a large bowl, mix sugar, egg yolks, and salt. Set aside. In a saucepan, bring cream and vanilla almost to a boil. Slowly add to the egg mixture and blend. Return to pan and cook to 176F (use a candy thermometer). Remove from heat. In a small bowl, mix gelatin and water and let sit for 5 minutes, and then melt in a microwave for 15 seconds. Add gelatin to egg mixture and stir. Pour through a strainer to remove any small particles. Pour into desired serving pieces and freeze. Thaw before serving.