Improvement work is underway on Albert Pier.
The project, delivered by Geomarine, will see the extended deck removed and the existing ramp placed onto a new steel frame.
Ports of Jersey says it's aimed at helping to keep the marina safe, accessible, and resilient for the thousands of people who use the harbour each year.
Harbour operations and vessel movements will continue as normal during the works, all Viviers will remain accessible, and the pier head will stay open for pedestrians and emergency vehicles.
Parking at the southern end of the pier will be suspended throughout.
Captain William Sadler, Jersey Harbour Master, said:
"These improvements are about making sure the marina continues to serve the people who rely on it every day, whether that's for work, leisure or simply enjoying everything our coastline has to offer.
"While there will be some short-term disruption, the long-term benefit will be a more resilient marina that's ready to support our maritime community for many years to come."
The work is expected to continue until January, before pausing for winter and restarting in the Spring.
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