Sembcorp Marine, the world's number two builder of offshore oil rigs, said on Tuesday its third-quarter net profit rose 73 percent as it worked through its large backlog of orders and recorded higher margins.

The firm said it expects ship repair demand to remain strong amid global tightness in yard capacity.

"The Group is in a strong net cash and balance sheet position and expects the current year's overall performance to be stronger than 2007," the firm said in a statement.

Sembcorp Marine earned S$140.9 million ($95 million) in the three months to September compared with S$81.4 million a year earlier.

The Singapore company said its order book stood at S$9.9 billion at the end of the third quarter, including S$5.5 billion of new orders since January this year.

Sembcorp Marine's large orderbook will ensure its yards remain busy until 2012