Bring water, wine, 1 teaspoon salt, and the bay leaf to a boil in a medium saucepan. Reduce heat, and simmer for 5 minutes. Add half the shrimp, and cook until opaque, about 1 minute. Using a slotted spoon, transfer shrimp to a plate, and let cool. Repeat with remaining shrimp. Cut into 1/2-inch pieces.
Whisk together lemon juice, vinegar, and remaining 1 teaspoon salt in a medium bowl. Pour in oil in a slow, steady stream, whisking until emulsified. Whisk in creme fraiche. Fold in shallot, chives, and shrimp. Cover with plastic wrap, and refrigerate for at least 30 minutes (and up to 4 hours). Just before serving, separate endive leaves, and thinly slice crosswise. Fold endive into shrimp mixture. Serve on crackers.