A design suitable for commercial and leisure use – with tidal challenges
Colas (France), part of the Bouygues Group
The Colas Group is a major French civil engineering firm specialising in road and rail track construction as well as ports and harbours.
Our team was needed to assist on a bid for a ‘design, build, finance and operate’ (DBFO) project for the development of a fishing port and marina at La Cotinière on the Ile D’Oléron off the south west coast of France.
The project included the construction of a new fishing harbour with full tidal access outside the existing tidally-restricted inner harbour. The second part of the project was for the development of two inner basins to create a leisure marina.
There are quite a few challenges in this location, one being the large tidal range and the constraints of the existing harbour, which dries at low tides. For a leisure marina to be viable, we felt it was necessary to create a marina where vessels could remain afloat at all states of the tide. However, without substantially deepening the basin, this would only be possible by holding water behind a tidal gate or sill. In turn, though, this would limit the tidal access window, which has an effect on the economics of the project. Our study and design skills were needed to optimize the design, balancing build cost against revenue for the marina.
We developed an innovative solution to maximise the access to the harbour, at a cost-effective build price.
The market study showed a high level of local demand for berths, with nearly all marinas in the region having a 5-10 year waiting list. This study gave a sound basis for our team to design a new marina that suited the local market, with all of the facilities and services that would ensure maximum appeal – and a sustainable tariff for berthing and associated services.
We provided the specialist marina input to the team allowing Colas to bid with a credible and viable project backed up by sound analysis
Our design allowed water to be impounded in the inner basin to maximise the marina’s potential, whilst maintaining the tidal access window of the original harbour.
If you’ve got a marina project or development in mind, let’s discuss how we can help.