McDowall Affleck was involved in the design, detailed documentation and construction of the Sorrento Quay performance deck and shade sail structure located at Hillarys Boat Harbour, in Hillarys, WA. The Performance Deck is an important upgrade and will be a major new attraction to the facility. Having been designed as a natural amphitheater it will provide podium seating, a covered stage area, as well as new public spaces. McDowall Affleck worked closely with the architect to develop the design of the decking area and shade sail structures, which was challenging due to the inaccuracy of the as-built geometry compared to the available documentation, as well as the in-service condition of the existing structure. A number of unknowns were acknowledged in the design and documentation, and McDowall Affleck was closely involved in the construction process, monitoring site works and addressing any issues that arose as required. Finite element modelling of the existing structure provided a clear understanding of existing capacity and allowed for an efficient yet safe design for the new project.