Seagoing vessel access to ports on eastern Sweden’s Lake Malaren is due to be substantially improved reports David Tinsley.
The access is set to be improved by the creation of a larger lock and deeper channel through the Sodertalje Canal, together with the modification and deepening of the Malaren fairways.
By allowing the passage of larger ships to the lakeside ports of Vasteras and Koping, companies and industries based in the Malaren region, and potentially also the Stockholm area should benefit from lower unit transport costs. The scheme also accords with government endeavours to foster a modal shift, largely on environmental grounds, and to relieve pressure on the heavily-trafficked road and rail networks.
KEY CONDUIT
Located immediately to the north, and inland, of the port of Sodertalje, and just to the southwest of Stockholm, the canal is 3.3 nautical miles in length and provides a conduit between the Himmarfjarden sea inlet and Lake Malaren, effectively linking the Baltic shipping lanes with Sweden’s industrial hub and major consumer market.
Today, the maximum dimensions for ships negotiating the serpentine fairways of the lake are 124m in length and the 17m beam. The current project, due to be completed by early 2020, will increase the scope to vessels of 160m x 23m.
The development entails the construction of a longer, wider and deeper lock at the canal entrance, the dredging of the canal, and the deepening and improvement of channels at critical areas on the lake, notably in the vicinities of Enkoping, Tedaro, Vasteras and Koping, and the narrow bridge passages at Hjulsta and Kvicksund.
SQUAT AND HEEL
Studies and modelling for the project have been conducted by technical consultancy SSPA Sweden in Gothenburg. The comprehensive investigations highlighted the effects of the phenomenon of squat in the shallow waters of the lake and canal, plus the added influence of heel for certain types of vessel, and the vital need to make due allowances when setting new navigational parameters.
The Swedish Maritime Administration entrusted the EUR 127 million(US$150m) contract for building the new lock and enlarging the Sodertalje Canal to Zublin Scandinavia, a Swedish subsidiary of the Austrian-headquartered Strabag Group.
The existing Sodertalje lock is 135m in length and 19.6m in width, with a water depth of 7.8m. Vessel draught is restricted to 6.8m, while maximum permissible hull dimensions are 124m x 17m, setting the limits for ships navigating Lake Malaren.
In addition to the construction of the new lock of 190m x 25m, to accommodate an increase in vessel size to 160m x 23m and the deepening of the canal section north of the lock to 8.2m, the Malaren fairways will be dredged to 8.4m. The latter depth provides for a nominal clearance of 1.4m to allow for squat, wind, and ship turn-induced heel angles, such that the future, maximum draught for Malaren navigation will be 7.0m.
SSPA devised a way of calculating the squat effect through an earlier model test study carried out with Swedish and South Korean partners under a joint industry project called SWaBE(Shallow Water and Bank Effects).
The ports of Vasteras and Koping are managed by a single company, Malarhamnar, which is targeting business growth on the back of increased vessel size capabilities. Malarhamnar’s traffic is diverse and includes chemicals, steel, forestry goods, petroleum products, biofuel, and grain, plus shortsea and feeder container services.
A notable example of the shipping industry’s response to the opportunities offered by the Malaren project is reflected in the design of a versatile new generation of oil/chemical product tankers of 150m x 22.8m ordered by Swedish shipowners represented in the Gothia Tanker Alliance. As embodied by the recently completed lead vessel, Furetank’s Fure Vinga, which offers 18,200dwt at the maximum, summer draught of 9.4m, the design can be loaded to 10,600dwt at 7.0m draught for shipments via the expanded Sodertalje Canal and improved Malaren fairways.
Source: Maritime journal