A skimmer pool closure assembly for closing off a swimming pool from a pool skimmer that is mounted to the pool adjacent a side wall opening includes a face plate attachable to either the pool skimmer or the side wall and having a configuration generally coextensive with the side wall opening. The ultrasonic probe design system includes an interface for inputting statement parameters, insonification requirements, and geometric constraints, with an engine responsive to the interface and configured to determine and provide an optimized transducer geometric design output. Scores represent a measure of relevance to the topic. The process also includes removing a portion of the LNG cooling loop as LNG product.