Work on the construction of a new breakwater structure at the mouth of Cowes Harbour has moved into the third stage of this 18-month coastal protection project.

The new breakwater is intended to transform the port into a true sheltered harbourage.

The latest phase of the operation, carried out during daylight hours by a
large barge and multi-cat, will run up to the start of August and
the Aberdeen Asset Management Cowes Week.

Following a recent agreement between Cowes Harbour Commission and
Boskalis Westminster, the fourth stage of construction on the breakwater
is now set to start after the Cowes Week regatta.

The Exclusion Zone that is in place around the submerged breakwater
and construction area will remain in place during the event, which runs from 2-9 August, .

All harbour users and competitors are strongly advised to
take careful note of the Cowes Local Notices to Mariners for the most
up-to-date information on the extent and shape of the Exclusion Zone,
which is shown by lit buoys and cardinal marks.

A 300 metre long
floating orange and black pipeline, also lit, is anchored parallel to
the breakwater on its northern side, and a 60 metre barge may be
positioned anywhere along the breakwater footprint.

Mariners are advised to enter or depart Cowes Harbour via the fairway
or Small Craft Channel.

The work so far

Cowes Harbour Commission’s appointed contractors Boskalis Westminster have completed the installation of an initial 1.5 metre layer of sand and gravel along the breakwater footprint (350m x 50m) and inserted a total of 11,000 wick drains to draw out water, thereby improving the ground bearing capacity of the seabed.

Captain Stuart McIntosh, Harbour Master at Cowes, said: ‘We are very pleased to report that construction on Cowes’ new detached breakwater is progressing extremely well and we have now commenced stage three of the 2014 works programme which is the placing of a geotextile membrane on top of the sand and gravel layer.

‘This phase of the operation, carried out during daylight hours by a large barge and multi-cat, will run up to the start of August and Aberdeen Asset Management Cowes Week as planned.’

Phase four

After Cowes Week, stage four will see the installation of the breakwater’s gravel core up to between 4 and 5 metres above chart datum using a trailing suction hopper dredger, floating pipeline and spraying pontoon.

When the crest of the breakwater is visible above the water surface, the spraying pontoon will then be utilised to spray gravel against the slopes of the breakwater.

The gravel will be left to consolidate for one month prior to being raised up to 5 metres above chart datum along the whole length of the breakwater.

By this September, and during a nine month period over the autumn and winter to allow for settlement of the gravel core, the breakwater will resemble a gravel spit and will only begin to take its final finished appearance during the 2015 works.

A spokesman said: ‘Cowes Harbour Commissioners are very grateful for the continued co-operation of local residents and assistance from all relevant parties during the construction of the breakwater, which will, once completed, protect the harbour and deliver a range of long-term benefits to the local economy.’

Pictures: The Cowes breakwater construction – laying the geotextile membrane; A cross section of Cowes breakwater. Credit: Boskalis Westminster

The Cowes breakwater at Low Water and High Water in September 2014. Credit: CHC/ Boskalis Westminster