THEY have been working hard letting boats through to Swansea Marina for the past 20 years.
And now the outer lock gates on Swansea's River Tawe barrage are set for a little TLC.
They will be renovated so they are fit for purpose for the next decade and beyond.
Between 14,000 and 18,000 boats pass through the lock gates every year on their way between the Maritime Quarter and the sea.
June Burtonshaw, Swansea Council's cabinet member for place, said: "The River Tawe barrage outer lock gates have been opening and closing for many hundreds of thousands of boats over the past 20 years.
"This has inevitably led to a lot of wear and tear and means major maintenance is needed to ensure the gates are in top working order for the next decade and beyond."
Contractors on site will use a giant crane to remove the lock gates from their hinges so the refurbishment work can be carried out. This follows on from work to upgrade the inner lock gates in 2011.
The works start on Monday, February 18, and are scheduled to take about five weeks. It means boats will not be able to pass through the lock gate area while contractors are on site.
The works also mean the Trafalgar Bridge will be temporarily closed from Monday, February 18, to the end of March for pedestrians and cyclists until the upgrade is complete.
The Swansea Yacht and Sub-Aqua Club and boat owners who moor their vessels in the Maritime Quarter have been informed.
Commercial fishing boats are being relocated to the estuary side of the barrage while the works are ongoing.
Mrs Burtonshaw added: "The start of the year is traditionally a quiet time for boat owners, so it makes sense to start the works soon and finish them in readiness for the arrival of the spring.
"The impact on boat owners and fishermen would be far worse if we didn't carry out the works now and the lock gates then failed in the peak season.
"The scheme also means the nearby Trafalgar Bridge will be temporarily closed to allow safe working and easy access to the site for the contractors.
"A clearly-signed diversion will be in place for pedestrians and cyclists while the works are ongoing."