The SS Matsonia, a Matson Inc. cargo ship scheduled to arrive in Honolulu Wednesday morning, lost power and was stalled about 550 miles north of Hawaii as of Wednesday evening.

A problem in the engine room cut off power on the ship, said Matson spokesman Jeff Hull. Matsonia engineers onboard were working to restore power.

There are 21 people on board the ship that was traveling from Oakland, Calif.

“We have experienced engineers on ship at all times capable of doing repair work,” Hull said. “So far they have been unsuccessful in repairing the problem in the engine room so there’s no power.”

There is an emergency generator to keep the lights on for the crew “but the ship doesn’t have enough power to get back on its own until the problem is resolved,” he said, adding that a tugboat has been dispatched should the ship need to be towed to the islands.

“If they’re able to rectify the problem, the ship could be underway and be back in port tomorrow (Thursday),” Hull said. If it has to be towed, there could be a delay of five to six days, Matson said in a letter to customers.

Hull said Matson will honor claims for perishables lost as a result of the incident.

Hull said the tropical depression east of Hawaii Wednesday was not a concern for the ship.

“These ships are designed to withstand high seas trans-Pacific storms. They have to go through storms (all the time),” he said. “It’s a big container ship. Weather is not the concern.”