In a medium bowl, stir together the boiling water, unflavored gelatin, and lime flavored gelatin mix until completely dissolved, about 1 minute. Set aside to cool until slightly thickened. This should take about 1 hour.
In a separate bowl, mix the mayonnaise, cottage cheese, and horseradish with an electric mixer until foamy. Stir in the pineapple, pecans and salt by hand. Fold the thickened gelatin mixture into the pineapple mixture. Pour into molds, and refrigerate until set, at least 2 hours.
To release gelatin from molds, dip the mold in hot water for 30 seconds to loosen, then invert onto a serving plate.
