Preheat oven to 350ºF with a rack in the center position. 

Place shrimp right side up on cutting board. Using a sharp paring knife, cut through the tail shell from the top of the tail to the bottom of the flipper, taking care to nog separate head from tail. Using your thumbs, open the tail flat, remove the vein, and gently pry the meat away from the shell, leaving it intact at the head. Set aside.

In a large mixing bowl, combine all of the remaining ingredients except crabmeat, salt and pepper, butter, dry sherry, and water. Mix until well incorporated. Gently fold in crabmeat, being careful not to break lumps. Season to taste with salt and pepper. 

Stuff tail of shrimp with a generous portion of the crabmeat stuffing; the tail should lay flat. Transfer to a large baking pan and drizzle with butter and sherry. Add water to the pan and transfer to the oven. Bake until stuffing is golden, 15-20 minutes.

Makes 6 servings.