Profits at cruise line operator Carnival almost tripled in the second quarter of the company´s fiscal year, courtesy of stronger than expected yields and amid a large drop in the company´s fuel costs.Second quarter net income jumped to $193m or 25 cents per share for the three months ended on 31 May, well ahead of the equivalent figure for 2014 of nice cents. The company had guided towards earnings per share of 16 cents.At $3.59bn the company´s quarterly revenues were nearly unchanged versus the same period of 2014, while costs decreased 5.3% to $3.3bn.Fuel costs plummeted by $194m in the second quarter, to reach $333m.In the second quarter so-called 'net cruise costs' excluding fuel increased by 6.1% versus the prior year, below guidance for a rise of between 6.5% to 7.5%.The chief factor behind rising costs was the increase in dry dock days. On the other hand, adverse currency effects subtacted 10 cents per share from earnings.Even so, the firm revised its guidance for full-year non-GAAP EPS upwards to a range of between $2.35 to $2.50.Management now expected third quarter EPS to come in at between $1.56 and $1.60, roughly unchanged from the $1.58 seen in the year-ago period.As of 15:00 shares of Carnival were down by 0.64% to 3,266p.