Cruise Writedowns a factor in lower Q3 earnings for Carnival Corp. By Tom Stieghorst / September 24, 2013 Share 1 -- Carnival Corp. earned $934 million in the key third quarter, down 28% from the $1.3 billion earned in the same quarter last year.Revenue of $4.7 billion was in line with last year, Carnival said.Carnival said it had impairment charges of $203 million to write down the value of two older Costa ships, its Ibero Cruises trademark and other items. Those were partly offset by a gain on fuel derivative contracts.Like other cruise lines, Carnival earns the bulk of its annual profits in the third quarter, which at Carnival includes the months of June, July and August. For all of 2013, Carnival said it expects to earn $1.2 billion.Carnival also reported income on a non-GAAP accounting basis, a method favored by some investors. By that measure, it earned $1.1 billion, down from $1.2 billion a year ago. Follow @tstravelweekly on Twitter.