Combine water and gelatin in a 4-cup measure.
Microwave to boiling, 2 1/2 to 4 1/2 minutes.
Drain oranges and pineapple, reserving juice.
Add enough water to make 1 cup.
Add to gelatin; stir in cranberry sauce.
Chill until thickened.
Combine mayonnaise and sour cream; stir in 1 cup of the gelatin mixture.
Pour sour cream mixture into an 8-cup ring mold; refrigerate to set.
Add oranges and pineapple to remaining gelatin.
Pour over fruit.
Refrigerate 4 hours.
Unmold and serve.