The company earned 392.17 million baht in the quarter, compared with 843.09 million in the same period last year, on revenue of 1.13 billion baht, a 43.5% decrease from 2 billion.

"This is due mainly to the reduction of the number of vessels to 21 - only half of the 42 we had in the first quarter of last year," Mr Wadia said yesterday.

"Another two vessels valued at US$45.9 million will be delivered within the second half of this year, resulting in a total of 23 vessels at the end of the year if no more ships are bought under the fleet rejuvenation plan that replaces aging ships," added Mr Wadia.

By the time the replacement programme ends in 2014, PSL expects to have 65 ships in service.

Also, a reduction in time charter rates contributed to the decline.

Time charter rates in the first quarter of this year averaged $12,425 per ship per day, a 14% decrease from $14,485 in the same period last year.

PSL managing director Khalid Hashim earlier forecast that time charter rates this year would average $12,500 per ship per day, as the supply of ships is rising faster than demand.

Mr Wadia said that demand was unlikely to drop. "But the biggest concern is that we have a new supply of ships [in the world market], so freight rates will not go up. The problem is the delivery of the supply of new ships," he said.

Operating expenses per ship per day averaged $4,963 in the first quarter, compared with $5,040 last year.

Mr Wadia said operating costs would come down for the rest of the year, with previous estimates at $4,750 per day.

"Expenses are down by around 8% per ship because older ships have been sold, and the younger ships require less cost to maintain," he said.

PSL shares closed unchanged yesterday on the SET at 18.4 baht in trade worth 52 million baht.