It Cost How Much?

From the San Fran Chronicle:
Coast Guard rescuers spent three hours and more than $9,000 on Thursday night searching for two men seen swimming from San Francisco's Aquatic Park to Alcatraz, all while the pair watched safely from the island, authorities said.
A boater spotted the two men, who turned out to be off-duty firefighters from outside the Bay Area, swimming toward the former federal prison around 8 p.m. and notified the Coast Guard, said Officer Mark Leahey, a Coast Guard spokesman.
"Vessels that were transiting near Alcatraz saw these two swimmers and called us and asked, 'Why are these two people swimming this late at night?' " Leahey said. "We obviously thought they might be swimmers in distress."...
Leahey said the search had cost the Coast Guard a total of $9,252. The men will not be billed.
http://www.sfgate.com/bayarea/article/Alcatraz-swimmers-hide-from-search-4675222.php
Even they used a helicopter (for an hour) and 2 boats, there is no way they used up over $9000 in fuel.
Coast Guard personnel are paid whether they work or not.
So, how did the Coast Guard come to the figure of $9252 in searching for the guys?