Simplify the following text for a Grade 10 native English-speaking person.
Original: It was originally intended that several of these destroyers would be built at Cockatoo Island Dockyard , but Williamstown Naval Dockyard had emerged as the sole builder of the vessels before the project was canceled .
Simplified: It was planned that some of these ships would be built at Cockatoo Island Dockyard , but only the Williamstown Naval Dockyard built the ships before the project ended .