Matson Inc. more than doubled its profit during the first full quarter it has operated as an independent company, but the gain was primarily due to a big expense that lowered profit a year ago.

Hawaii’s largest ocean cargo transportation firm and former subsidiary of Alexander & Baldwin Inc. announced Wednesday that it earned $19.1 million in the third quarter compared with $8.7 million in the same period last year.

But the increase was mostly due to a $9.7 million expense largely for scaling back service in China during last year’s third quarter that reduced year-ago profit.

Matson CEO Matt Cox said the company’s performance during the July-September period was stable and showed some encouraging but very early signs of improved shipping volume to Hawaii.

“All in all (it was) a steady, satisfactory quarter for Matson,” he said on a conference call with stock analysts.

Revenue grew to $401.4 million in the third quarter from $380.6 million a year earlier.

Revenue growth stemmed from slightly more Hawaii shipping, extraordinary volume in Guam and strong volume and rates for Matson’s continuing service in China.

Hawaii container volume edged up 0.8 percent, to 35,700 containers in the quarter from 35,400 containers a year earlier. Cox called the 300-container increase encouraging, though he said the state’s construction industry isn’t making a big enough rebound to boost container volume significantly.

“The slight gain we saw on (Hawaii) container volume during the quarter is encouraging, but we’re hesitant to say we have reached a bottoming and that large volume gains are in our forecast,” he said.

Matson enjoyed a 12.7 percent increase in Hawaii automobile shipments, but that was primarly due to the timing of rental car fleet replacements, Cox said.

In China, Matson shipped 17,100 containers in the quarter, up 11 percent from 15,400 containers a year earlier. And in Guam, volume surged 91 percent to 6,500 containers from 3,400 containers primarily because rival Horizon Lines pulled out of that market and another carrier has yet to step in.

Matson expects a new competitor to enter the Guam trade, but Cox said he doesn’t know when that might happen.

Joel Wine, Matson’s chief financial officer, said the company expects Guam business and strong China freight rates could double Matson’s ocean transportation operating income in the fourth quarter.

During the third quarter, Matson had higher expenses from dry-docking one of its largest ships, which resulted in the company using two smaller ships in its place. The company also had expenses of $300,000 related to its separation from A&B that occurred June 29.

One of Matson’s goals as an independent company is to reduce its debt. During the third quarter, Matson lightened its debt load by $44.2 million, leaving it with total debt of $328.6 million.

Matson also is preparing to reduce the average age of its fleet by adding two new ships in the next three to five years at a cost of roughly $200 million each.

Shares of Matson stock on the New York Stock Exchange closed Wednesday at $20.93 before the earning’s announcement, down 69 cents from Tuesday.

Since the separation from A&B, Matson stock has closed between a high of $27.83 on July 2 after the first day of trading and a low of $20.16 on Oct. 1.