Rinse cranberries in colander, removing soft and spoiled berries. Using a chopper or food processor, chop cranberries to a fine, small consistency. Put in a medium-sized bowl and sugar; stir and let sit for 10-15 minutes.
Drain crushed pineapple in colander. Add cranberry mixture and remove as much liquid as possible.
In a separate, larger bowl, beat whipping cream until fluffy. Fold in cranberry/pineapple mixture, mixing well. Refrigerate for 1 hour before serving.