The high-speed Golden Gate Ferry M.V. Del Norte will need an overhaul of its engines sooner than planned thanks to the continuing absence of its sister boat the M.V. Mendocino, which has been missing in action since April 2015.

The Del Norte has picked up the slack, accumulating triple the operating hours originally planned for the vessel. That extra duty has taken its toll.

Now Golden Gate officials have had to set aside $150,000 for an overhaul of its four engines. Of that, $120,000 is from federal dollars, another $30,000 from the district. That work will commence within the next two months. The work will be done in-house at night over three weeks, officials said.

“There will be no interruption in service,” said Priya Clemens, Golden Gate Ferry spokeswoman.

The 448-passenger high-speed M.V. Mendocino — added to the fleet in 2001 — arrived in San Diego last year to undergo a $6 million upgrade, including a re-done interior and new water jets.

But the new jets installed on the Mendocino intended to propel the vessel forward instead sent it in reverse, because the system spun in the wrong direction. The mistake was discovered in early October as the boat was tested.

Golden Gate Ferry officials allege Australian-based Incat Crowther Ltd., the original designer of the ferry, provided the wrong design for the replacement of water jets and the gearbox. Ferry attorneys have been in touch with the company, but don’t yet know if it will accept responsibility, or if the matter will have to be litigated.

The $500,000 gaffe means the return of the high-speed ferry to Larkspur will be delayed until spring or early summer, and patrons have to continue to use the smaller 400-passenger Del Norte and other boats for service. The Mendocino was to have returned by the end of 2015. The Del Norte was the district’s original high-speed ferry and began plying the bay in 1998. The high-speed ferries make the Larkspur to San Francisco trek in 30 minutes.

Meanwhile, the M.V. San Francisco — a slower Spaulding-class vessel that went into service in the early 1970s as Golden Gate launched its ferry service — is back in Marin as of earlier this month after major upgrades.

It can carry more than 700 passengers and is used to take passengers from Sausalito to San Francisco and is used out of Larkspur for weekend service and to take baseball fans to AT&T Park.

While the district has updated the main propulsion system on the ferry over the years, there has been little done to upgrade or refurbish the interior and exterior passenger spaces, other than routine maintenance and repairs, officials said.

Among the new items: indoor and outdoor seats, deck covering, carpeting, ceilings, wall paneling, lighting, the public address system, restrooms, refreshment stand, security cameras, paint and windows. All its machinery, with the exception of two generators, also was replaced. There are also new bike racks on the lower deck and a new modern lift for people with disabilities.

The work cost $20 million, the tab picked up by federal dollars. A new vessel would have cost at least $27 million.

After touring the boat before it went in for the work, Golden Gate Bridge board member Jim Eddie commented: “It smelled like tobacco and diesel. I couldn’t wait to get off.”