A small boat travels there every hour is it a simple subject, a complete subject, a simple predicate, a complete predicate

Simple subject = boat

The simple subject is the specific subject without any modifiers that describe the subject.

Complete subject = A small boat

The complete subject includes the simple subject and any modifiers. The modifiers describe the subject and are usually adjectives.

Simple predicate = travels

The simple predicate is the main verb. in this case it is an action that tells what the boat is doing.

Complete predicate = travels there every hour.

The complete predicate is the main verb along with any modifiers and other details that describe what is going on.