A stricken Honolulu commuter ferry that began running rough 11 days ago will remain out of service for the rest of the week as mechanics try to fix an engine problem.

A second ferry will continue operating as scheduled, but the problems mean two of six daily trips between Kalaeloa and Aloha Tower are canceled for the week. Special express buses will replace the missing ferry trips.

The engine problem is the second lengthy breakdown for the Rachel Marie, one of the twin 72-foot catamarans that began ferry operations in September as a program dubbed TheBoat. An engine that failed in November was replaced with a rebuilt one from the Mainland.

"Apparently, this engine is going through an adjustment period," acting city transportation director Wayne Yoshioka said. "It's just not running right."

The city's ferry operator, Hornblower Marine Services, is paying for the repairs and will make up for the lost days, Yoshioka said. The ferries are being operated for a one-year pilot program funded by $5 million in federal grants.

Yoshioka said he was thankful that some passengers continue to ride the boat that still runs well, known as the Melissa Ann.

"We have a core of riders that is sticking with us through these difficulties, and we appreciate their patronage," he said.

City Council Transportation Chairman Nestor Garcia said the breakdowns are troubling.

"Isn't there a lemon law or something?" he said. "Can't we get a trade-in?

"They better isolate the problem and get it fixed."

If the problems continue, it could be very difficult to justify spending city money to continue the ferry service after one year, he said.

"I don't know, based on this record," Garcia said. "I regret saying that because I've always thought we need to have something ongoing for two or three years in order to really establish in the minds of people that this is a viable, reliable option. It's very tough for me to live up to that if, in the first year, you're not delivering."

The daily 6 a.m. sailing from Kalaeloa, and 5:20 p.m. sailing from Aloha Tower, have been canceled until repairs are completed.

Reach Johnny Brannon at jbrannon@honoluluadvertiser.com.