US-listed Nordic American Tankers said on Thursday that it had struck a deal to add another vessel to its suezmax fleet.

The agreement for the unidentified South Korean-built ship takes the Herbjorn Hansson-led shipowner’s suezmax-only fleet to 20. Seven of them are aged more than 15 years.

NAT said the vessel had been operated and well-maintained by a “top shipowner” for the last six or seven years.

The company said the ship was bought on a charter-free basis and would be financed with a sale-and-leaseback deal. The cost of the deal was not disclosed.

“The vessel will be included in our fleet within this quarter, entering a strong market for our ships,” the company said in a statement.

Last month, NAT said time-charter-equivalent earnings in the low season were 50% ahead of the average for the past 10 years despite Saudi Arabia-led production cuts.

It did not give figures but said in August that 57% of its spot voyage days for the third quarter had been booked at an average TCE of $34,800 per ship.

On Wednesday, the Baltic Exchange listed suezmax TCE rates at $54,755, up $3,622 from the previous day.

Rates have surged in the last week to the highest levels since June, in line with other tanker sectors, with strong demand for tonnage in the Arabian Gulf and West Africa, brokers said.