Drilling begins in Portsmouth for arrival of Navy’s latest carriers

The next step in prepar­ing Portsmouth Naval Base to be the home of the biggest war­ships ever built for the Roy­al Navy began last week.

The spe­cial­ist drilling rig being used in the work to pre­pare Portsmouth Naval Base for the arrival of the new air­craft car­ri­ers [Pic­ture: Crown Copyright/MOD 2012]
Source: Min­istry of Defence, UK
Click to enlarge
Artist’s impres­sion of the new air­craft car­ri­ers [Pic­ture: Air­craft Car­ri­er Alliance]
Source: Min­istry of Defence, UK
Click to enlarge

A spe­cial­ist rig began six weeks of drilling on Fri­day, sam­pling the seabed in the har­bour and in the Solent.

The tests will pave the way for major dredg­ing work in a cou­ple of years’ time to allow the 65,000-tonne HMS Queen Eliz­a­beth and Prince of Wales air­craft car­ri­ers to safe­ly and eas­i­ly enter the har­bour.

The two flag­ships are 10,000 tonnes heav­ier than the last tra­di­tion­al-style car­ri­ers to serve the Roy­al Navy — HMS Ark Roy­al and HMS Eagle, which were both decom­mis­soned in the 1970s — and much larg­er than any cur­rent war­ship based in Portsmouth.

The exist­ing chan­nel used by ships needs to be widened and deep­ened to accom­mo­date the new car­ri­ers. The berths in the base itself also need to be exca­vat­ed and a suit­able turn­ing cir­cle pro­vid­ed in the north of the har­bour — the draught (the depth of a loaded ves­sel in the water tak­en from the lev­el of the water­line to the low­est point of the hull) of the sis­ters will be 36 feet (11m).

Sur­vey work was car­ried out a decade ago — not least on the wreck site of the Mary Rose to ensure that every­thing of his­tor­i­cal impor­tance had been recov­ered from Hen­ry VIII’s flag­ship.

In addi­tion, a detailed envi­ron­men­tal analy­sis of the har­bour and its approach­es was car­ried out in 2004, while the bridge sim­u­la­tor at HMS Colling­wood has been adapt­ed to test the new route to prove that the car­ri­ers can enter or leave the har­bour in a range of tidal and weath­er con­di­tions — so far more than 180 sim­u­lat­ed arrivals and depar­tures have been con­duct­ed.

Cap­tain Iain Green­lees, who is in charge of the trans­for­ma­tion project ahead of the ships’ arrival, said the work by rig ‘Deep Riv­er’ would build on exist­ing under­stand­ing of the geol­o­gy of the har­bour and its approach­es:

“Work so far has iden­ti­fied the route which bal­ances best nav­i­ga­tion­al safe­ty, the low­est envi­ron­men­tal impact and cost,” he explained.

“The analy­sis of these final bore­holes will com­plete our detailed under­stand­ing of the work that will be required and allow us to apply for final approvals — and run a com­pe­ti­tion for the work.”

The Queen Eliz­a­beth is due to be launched in 2014 and will arrive in her future home of Portsmouth two years lat­er; the Prince of Wales is due to join the fleet towards the end of the decade.

Next year work will begin to replace tele­phone cables between South­sea and the Isle of Wight, fol­lowed in 2014–15 by major dredg­ing work. Cap­tain Green­lees said around three-and-a-half mil­lion tonnes of seabed need to be moved.

The Deep Riv­er rig will drill 27 bore holes to a depth of 104 feet (32m) along var­i­ous parts of the pro­posed route. The rig will be bright­ly lit and will be oper­at­ing 24-hours-a-day.

It will need to dig five holes in the har­bour entrance which will cause some minor delays, but Queen’s Har­bour Mas­ter Com­man­der Nigel Hare said every effort has been made to keep dis­rup­tion to a min­i­mum — includ­ing sus­pend­ing work at week­ends — and 50 res­i­dents of Spice Island were being informed of the impend­ing work.

Com­man­der Hare added:

“This is clear­ly impor­tant work in the run-up to the new car­ri­ers arriv­ing in Portsmouth.

“It’s hoped that har­bour users and local res­i­dents will under­stand the rel­a­tive­ly short-term incon­ve­nience of the rig set against the much longer-term ben­e­fit of the project to the har­bour — and the city.”

Press release
Min­istry of Defence, UK

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