The phrase "a vast fleet of" is correct and usable in written English.
It can be used when describing a large number of vehicles, ships, or aircraft belonging to a particular organization or entity.
Example: "The navy showcased a vast fleet of ships during the annual maritime parade."
Alternatives: "a large armada of" or "an extensive collection of".
Global gloom means there is a vast fleet of used superyachts for sale.
A vast fleet of tankers would be needed to refuel warplanes.
A vast fleet of liners, ranging from passenger-cruise vessels to refrigerated cargo ships, continued to cover the world.
The Simpsons has a vast fleet of supporting characters who, even to this day, are richly drawn enough to shoulder entire episodes.
A vast fleet of pianos is expected to arrive in Cincinnati next month, part of the largest order — by number of instruments — ever filled by the Steinway & Sons piano company.
The journey culminated in the encampment in the famed wagon wheel circle of a vast fleet of Airstreams in the shadow of the Great Pyramid of Giza, like a congregation of silvery metal worshippers.
The comments came one day after Barack Obama took the largest step of any U.S. president to date and delivered a historic action plan to rein in emissions from America's vast fleet of 1,600 power stations.
The security demands would entail too much upheaval to the regular schedules for China's vast fleet of heavily used high-speed trains, they said.
As a result of the growing attention on the possibility of terror attacks using trucks, officials of chemical and fuel hauling companies were scrambling yesterday to find better ways to secure the vast fleet of trucks and rail cars carrying chemicals and fuels around the country.
He'll be spending many billions in the coming years to upgrade Exelon's vast fleet of aging power plants.
Much of Obama's promise depends on his plan to rein in emissions from America's vast fleet of power stations.
