Today at between 14.30 – 15.00, HMS Queen Elizabeth is due to cast off lines ready to depart from the fitting out berth in Rosyth Dockyard to begin sea trials. Taking the ship out of the basin and down the river Forth will be a complex and delicate evolution.
Before HMS Queen Elizabeth can put to sea, she has to have a certificate of seaworthiness. This is a basic safety requirement and ensures the hull is watertight and the propulsion and steering are functioning correctly. Although she has extensive automated centralised safety systems, fire-fighting, escape and lifesaving equipment must all be inspected and proved to be working correctly. The scale of the ship makes such tasks a considerable job, for example, there are 750 watertight doors on the ship, each requiring 3-4 man hours of testing. Checks to obtain sign off on this important paperwork have continued right up to the last minute before sailing. Some parts of the ship were constructed almost 8 years ago (in separate blocks around the UK, before arriving for assembly in Rosyth). For the past weeks, the ship has been a hive of activity as everything is re-checked and tested. Finally, before departure, temporary services such a ventilation, power supplies and lighting used by the building contractors must all be removed along with waste materials, scaffolding and tools.
Through the eye of the needle
A simple simulation showing the approximate plan for departure.
To leave the fitting out basin, the ship must be swung around using tugs and then carefully towed out through the very narrow tidal lock. A high tide is required to give the ship maximum clearance over the lock gates. There will just 50cm between the keel and the gates. This operation will be challenging, has extremely fine tolerances can only be conducted in light winds. The main hull of the QE will fit through the lock with a tiny clearance of just 35cm on either side. The blocks used to build the ship were floated in through this lock but the completed vessel is of course, much longer, heavier and has very large overhanging decks. The operation will call for the use of 11 tugs and considerable time has been spent planning the evolution and rehearsing in a simulator.
Ducking under the bridges
Once out of the basin the ship will go to anchor for several hours, awaiting low tide (just before midnight) which is needed to pass safely under the bridges. She will proceed at no more than 4 knots, any faster and suction effect pulls the ship toward the riverbed, a shallow water phenomenon known as ‘squat’. An extensive survey effort to determine the clearance under the bridges and depth of water has been conducted by an Army and Naval Hydrographic team. (You can read about it in more detail here). Modern laser range-finding methods have been double checked by the captain himself using his own sextant (patented in 1845).
Both road bridge decks flex in the wind and can move up or down by as much as 3 meters, depending on the wind strength and loads. The surveys concluded there is about 2 meters clearance between the highest fixed point on the ship (the main Type 1046 air search radar) and the road bridge decks at low tide. Once past the bridges, QE will anchor downriver in Kirkcaldy Bay for a time. As is standard with all new ships, various checks will be conducted to see how the ship has flexed or settled after being in open water for the first time. The process from leaving the fitting out basin, to anchoring off Kircaldy will take more than 10 hours.
The pole mast that carries communication aerials on the aft island was designed with bridges in mind. It is hinged so it can be tilted forward 60º by hydraulic rams.
The narrow lock that the ship must traverse to leave the basin at Rosyth.
The view from basin, looking South East down the Forth estuary towards the three bridges the ship must pass beneath.
Initial sea trials
HMS Queen Elizabeth is not yet commissioned into the Royal Navy, remains the property of the Aircraft Carrier Alliance flying the Blue Ensign until it is agreed she meets specification and is formally handed over. Captain Jerry Kyd has responsibility for the ship but must operate under the direction of the sea trials manager appointed by the builder. The initial trials will be conducted in two phases in the North Sea, mostly between the Moray Firth and Fair Isle. Phase 1 is expected to take around 6 weeks and will concentrate on proving the propulsion, power and auxiliary systems. The ship needs sea room for full power trials and will also be conveniently out of the public gaze, allowing the MoD to control information about her progress.
Another significant milestone will be achieved when the first aircraft to lands on the carrier. A Merlin Mk2 of 820 Naval Air Squadron have this honour, around 4 days after QE puts to sea and will provide the first opportunity to conduct personnel and stores transfers.
When complete, the ship will come alongside in Rosyth for the builders to rectify any issues discovered during trials. Assuming this only takes a few days, QE will depart again for Phase 2, which will focus on proving mission systems, radars and communications. Expected to take around 5 weeks, when phase 2 is complete QE will then set course for Portsmouth to make her grand entrance into her homeport for the first time. The dredging work and construction of the new Princess Royal Jetty is now complete and Portsmouth Naval Base is ready to receive the ship.
The sea trials plan is ‘subject to change’
The ship is essentially a prototype design and going to sea will inevitably throw up a few unexpected issues. The discovery of defects, or perhaps even fewer defects than expected, may result in changes to the program. However, if QE is able to keep to this approximate schedule then she would be expected in Portsmouth in late September or early October. It should be noted the project still remains well on schedule to meet the agreed target of delivering the ship to the RN by the end of 2017
Once home, QE is expected to remain in Portsmouth for around 8 weeks for further defect rectification. It is planned to conduct heavy weather trials in the North Atlantic in the first quarter of 2018 and HMS Queen Elizabeth should achieve Initial Operating Capability by the end of 2020. For more detail on the long-term plans, see the infographic – Timeline for delivering carrier strike
Last time it was done – from the BBC archive, HMS Ark Royal on sea trials in the North Sea, 1985.
Related articles
- Britain’s new aircraft carriers are a cause for celebration (Reaction)
- Aircraft carriers: Their point, purpose and power (Save the Royal Navy)
from Save the Royal Navy http://www.savetheroyalnavy.org/hms-queen-elizabeth-sails-for-the-first-time-today-heres-the-plan/
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