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News - 27/08/14

Installation of breakwater gravel core

D2 sprayer bargeWork on the new Cowes breakwater progresses extremely well with CHC’s contractors Boskalis Westminster currently on stage 4 of the 2014 programme, the installation of the breakwater’s gravel core up to approximately 4 metres above chart datum. 

The dredger Sospan Dau delivers up to to five loads of gravel per day which is then sprayed onto the breakwater footprint via the floating pipeline and spray nozzle located on the D2 barge. The barge is secured with anchors and anchor wires that run to the extremities of the Exclusion Zone. A total of 40,000 cubic metres of gravel will be laid over a period of approximately four weeks. On completion of this stage the breakwater will be visible at all times, apart from at spring high waters. 

CHC would like to remind all harbour users that the Cowes Breakwater Project construction programme is wholly contained within the Exclusion Zone which is marked by large, lit navigation buoys; any vessel not involved in the works shall remain outside of the Exclusion Zone at all times due to the presence of works equipment, mooring wires above and below the surface, obstructions and a growing gravel bank.

LNTM No 21 (T) of 2014
Breakwater Exclusion Zone extendedThe breakwater Construction Zone has been extended into the area of small craft moorings to facilitate the required mooring arrangement for the D2 works barge when all mooring wires will be contained north of the breakwater. Two additional yellow marks have been deployed along the boundaries of the extension; an 80m section of floating pipeline has also been anchored on the eastern boundary of the Exclusion Zone.

Please read Cowes Local Notice to Mariners No 21(T) of 2014 for more information on the fourth stage of works, the Exclusion Zone diagram, plus mark positions and light characteristics of the Exclusion Zone buoys.

Sensor installation
Two sensors have recently been inserted into the centre of the breakwater; these log water pressure every 10 minutes. In order to allow for retrieval of the sensors they have been installed in plastic duct work.

After some four weeks the sensors will be removed and the data downloaded. This data will give Boskalis Westminster insight as to the amount of and speed of settlement in the breakwater’s gravel core. These two factors will allow Boskalis’ geotechnical engineers in the Netherlands to predict the final settlement and total settlement time for the breakwater.

View of breakwater under construction from the bridge of Red Funnel's ferry Osprey
View of breakwater under construction (with tide height of 3m) from the bridge of Red Funnel’s ferry Osprey

See our Cowes Breakwater Image Gallery for more photos.