Bring a large pot of lightly salted water to a boil. Add the pasta, and cook until tender, about 10 minutes. Drain, and rinse under cold water to cool. Transfer to a large bowl, and set aside.

In a small bowl, mix together the mayonnaise, vinegar, olive oil, salt and pepper. Pour over the pasta and stir to coat. Add the crab, shrimp, tomatoes, cucumber, black olives and bell pepper; mix gently to coat with the dressing. Taste, and adjust seasoning if desired. If the pasta is too dry, mix in more mayonnaise.