Opal was originally designed by the naval architecture firm of Cox & Stevens[1] as the steel-hulled motor yacht Coronet for American businessman Irving T. Bush.

[2] This vessel was named after the smaller schooner yacht Coronet of 1885, built for Irving's father Rufus T. Bush and known for its victory in an 1887 transatlantic ocean race.

[6] From 1931 through the end of the 1930s, Coronet stayed in south Florida, in and near Miami, maintained and ready for service, yet inactive.

Early in October 1941 it sailed to the Charleston Navy Yard for installation of new sound detection equipment before returning to action against German submarines in the Caribbean Sea.

[2] In 1943, the US Navy reassigned Opal to serve as a training ship for Ecuadorian naval crews.