Bosun's Bass, an artwork and soundwork by Tim Hawkinson, is being installed over a hole on Pier 15 at the Exploratorium, and will be on view by Saturday Aug. 12, delayed from July 25th due to a needed repair. Made from a shipping container, Muni bus bellows, and a bicycle, it's activated by the tides and creates an eerie, high-pitched sound similar to a bosun's pipe, a type of whistle used by mariners.