From the news article. http://www.theguardian.com/world/2014/apr/07/baby-girl-rescued-us-navy-warship-lyra-kaufman?view=classic

"The frigate was expected to arrive in San Diego midweek, Coast Guard petty officer 2nd class Barry Bena said.
The Kaufman's Rebel Heart was sunk by authorities after taking on water.

Authorities decided to sink the Rebel Heart because it was taking on water, Bena said."