Premier Marinas' Port Solent marina has new, dedicated lock pontoons by Walcon on both sides of the lock. Each 30 metres in length, they feature distinctive timber panel skirting to withstand the constant manoeuvring alongside. However, building and fitting lock pontoons of this type can be a complex and challenging process.
For this project, the pontoons were built to allow them to reuse the existing wall columns, thereby avoiding the need to shut down the entire lock for an extended period in order to fit new ones. This required a detailed survey to establish the exact positions of the Universal column guide piles. The pontoons themselves needed to be narrower than conventional walkway pontoons so as to maximize the space available for boats in the lock. They also required a high freeboard to make mooring and access to and from the boats alongside as easy and safe as possible.
To achieve this, the pontoons were built using Walcon’s 700mm finger floats with space frames above to deliver a full metre of freeboard. To ensure that this top-heavy structure was stable required having pile guides at two levels. The space frame was helpful with this, enabling the positioning of the guides at the top and the bottom of the space frame, keeping them out of the water (and so easier to maintain) and at the same time far enough apart to provide the necessary stability.
Throughout the works Walcon ensured that the lock was kept operational as much as possible, minimising disruption to Premier Marinas and its berth holders. The new pontoons were assembled offsite and delivered directly to the lock as their predecessors were being lifted out and loaded onto lorries for immediate removal and scrapping. The pontoons were replaced in pairs, one a day with the lock immediately reopened once the operation was complete. Once all the units were in place on one side of the lock they were commissioned and some final works undertaken to ensure that they moved up and down smoothly across the full tidal range. The entire operation was then performed again on the other side of the lock to complete the project. More information at https://www.walconmarine.com/projects