Kevin Costner teaches Ashton Kutcher a thing or two about saving people at sea in the goofily-named THE GUARDIAN, which is all about the Coast Guard. The plot closely resembles past flicks like AN OFFICER AND A GENTLEMAN and TOP GUN and even Clint Eastwood's HEARTBREAK RIDGE. It also is too long, and will lose some viewers before the end, which is loosely based on a real rescue. Costner at least plays his age, much as he did in TIN CUP, and looks reasonably grizzled throughout. Sela Ward plays his ex-wife. Kutcher is less than convincing as his prize student, but that's Kutcher. He's just too damned girly to be playing a Richard Gere role. THE GUARDIAN is a time killer, if nothing else.