Daewoo Shipbuilding & Marine Engineering Co., the worl's second-largest shipyard by sales, posted a third-quarter profit on lower steel costs and increased construction of offshore structures.Net income was 191.3 billion won (US$166 million) in the three months ended September, compared with a loss of 84.9 billion won a year earlier, the company said today in a regulatory filing. That was more than the 180.2 billion won median of 20 analyst estimates compiled by Bloomberg. Sales gained 17 percent to 3.1 trillion won.