Shrimp Dip

1 (6 ounce) can lump crabmeat, drained and picked over to remove bones

2 (6 ounce) cans baby shrimp, drained

4tablespoons light mayonnaise (or more to taste)

1 (8 ounce) package low-fat cream cheese, softened

1⁄2 cup butter, softened (not margarine)

garlic powder (to taste)

onion powder (to taste)

1tablespoon of finely minced water chestnut

1 -2tablespoon finely minced and lightly sauteed onion