We now have some more precise details on HMS Queen Elizabeth’s maiden entry to Portsmouth early tomorrow.
If conditions for an entry are good, the ship will leave Outer Spit Buoy at 6.49am and pass Round Tower at 7.09am.
The entry will be accompanied by a flypast of Fleet Air Arm Merlin and Wildcat helicopters, plus Hawk jets of 736 NAS from Culdrose.
The carrier is due to begin berthing at the new Princess Royal Jetty about ten minutes later, though the whole process – including getting the specially-built brow across – could take up to two hours.
The entry has been practised many times – and in many different weather and tidal conditions – in the Bridge Simulator at HMS Collingwood.
The simulator’s manager, David Goddard, and Lt Barry Crosswood, HMS Queen Elizabeth’s 2nd Navigator, have provided the following details:
The approach channel to Portsmouth has been widened from its original 210 metres to 450 metres, and the channel has been straightened as much as possible to avoid large course alterations.
From full ahead to full astern, it takes roughly two nautical miles to bring the 65,000-tonne carrier to a stop. The entry therefore will be “slow and methodical”.
The navigable channel dredged for the carrier is 100 metres wide.
The ship’s beam (width) at the waterline is 40 metres.
The width of the flight deck is 70 metres and with the islands offset 25 metres to starboard, they actually sit over the water.
The most critical part of the entry will be as the ship passes through the harbour entrance between the Round Tower and Fort Blockhouse (on the Gosport side) – just 210 metres across.
To visually ensure that the ship remains within the channel, three pairs of navigation lights – Goddard’s Beacons, named after the bridge simulator manager – have been positioned at the northern end of the harbour.
These beacons take into account the offset of the bridge; the Captain and Navigator will use these to judge where the ship lies in relation to the centre of the channel and whether the ship is drifting to one side or the other. The bridge should be aligned with the middle pair of beacons.
The wind limit is 15kts. The carriers will normally enter and depart the harbour around the time of high water and when the strength of the tidal steam in the harbour entrance is slack (at the minimum strength).
The decision to enter harbour will probably be made before passing between Horse Sand and No Man’s Land Forts, and will take into account the wind speed and direction, the tidal conditions, the sea state, and the range of visibility – the beacons need to be visible from the bridge.
Six tugs will be escorting the ship into harbour to assist as required and manoeuvre the ship on to her berth in the naval base. Once the ship passes Outer Spit Buoy they are committed to entering harbour.
If you’re planning on coming to view the historic occasion, road congestion is expected near the Portsmouth/Southsea seafront and some roads, especially in Old Portsmouth