06 Oct - High and dry
RRS Ernest Shackleton is in C Dock, Portsmouth Naval Base.
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The lock gate at the east end of the dry dock is known as a casson and unlike the majority of lock gates is designed to float and be moved out of the way when a vessel is required to pass through. The casson at the eastern end of C lock was slowly moved back into place on Sunday afternoon, once the Ernest Shackleton was in position, and then filled with water (flooded) and slowly sunk until it fitted into place. The move is carried out using winches on the dockside and wires attached to the casson. The casson also acts as a bridge across the end of the docks. |
On Monday morning the dock was slowly pumped dry and the Ernest Shackleton settled onto the blocks, so carefully laid out the previous week. One method used to determine just when the ship had settled was to dangle a piece of wood over the ships side, floating in the water, and once the ship was on the blocks the tension in the rope holding the wood would increase as the water level started to drop in relation to the ships side.
Once the dock bottom was safe to enter, the Captain, Chief Officer, Chief Engineer and a DNV Classification Surveyor completed an inspection of the hull, checking to see the condition of the steel work and paint work and looking for any obvious signs of damage.
Once this is complete then the job of cleaning the hull can start, this involving teams with high-pressure hoses (operating at between 3000-6000 psi) who blast off any growth and dirt that has accumulated since the vessel was last dry-docked.
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The Ernest Shackleton on the blocks, overall in the dry-dock. There is a lot of work to be carried out on the hull of the vessel, with the five thrusters, the propeller, rudder, water intakes and hull penetrations. Click on the image to enlarge it. |
A view of the stern of the ship, showing the size of the dry-dock in comparison to the size of the ship. The dry-dock is able to receive an aircraft carrier sized vessel! Click on the image to enlarge it. |
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A view of the propeller and rudder. If you look closely you may just spot a worker inside the propeller! Click on the image to enlarge it. |
The work on our main 50 Tonne crane continues, with it being rewired following the upgrade of pumps and motors (which will give the crane a greater speed of operation). Numerous tanks and void spaces have been opened up and entered for inspection and cleaning where required, and both the ships fresh water tanks (known as potable water) were drained down for inspection and replacement of a leaking valve, and these will then be refilled and chlorinated to kill of any bacteria (as will the whole fresh water system around the vessel).
At 0700 each morning the dockyard is filled with the eerie sound of whistles being blown as 'all hands' on the naval vessels in the dockyard, are called to work. Throughout the week we have enjoyed good weather, with generally fine warm days and cooler evenings. The only rain has been at night earlier in the week.
Also in Portsmouth at the moment is HMS Endurance, the Royal Navy's Antarctic vessel, completing her refit and preparing for the forthcoming season.
RRS James Clark Ross has now completed the transit from the UK to the Falklands, having arrived on Saturday, and is now preparing for her first science cruise of the season. She will also be calling into King Edward Point, Bird Island and Signy, heralding the start of the 2002-2003 Antarctic season!
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....and (almost!) finally, here is a picture taken of a main sea-water cooling intake pipe. Seawater is pumped into the the ship and used to help cool the engines. As can be seen from the image, it has suffered from a build up of marine life, mostly mussels, and this will in turn restrict the flow of water to the engines. The pipe will have to be removed for cleaning. Click on the image to enlarge it. |
Portsmouth Dockyard
The first dock was built in 1194 and the yard was enclosed by a wall on the orders of King John in 1212 (three years before he was forced to sign Magna Carta).
Portsmouth Dockyard has been in the forefront of technological development for over 500 years. Here was constructed the world's first dry dock (1495), the first rolling mills were developed locally to make iron bands to reinforce wooden masts. Marc Brunel (father of Isambard Brunel) invented the first steam powered industrial production line for the manufacture of wooden pulley blocks (10 unskilled workers were able turn out the blocks that had previously required 100 skilled men - the mills turned out 130,000 pulley blocks a year).- and the revolutionary steam turbine powered HMS Dreadnought was built here at the beginning of the 20th century.
Much of the Georgian Dockyard is open to the public, with a single entrance fee giving access to HMS Victory, HMS Warrior and to the Mary Rose, along with entry to the numerous museums and displays housed in the many old buildings on the site. It also allows for a one hour boat trip around the harbour to view the modern vessels that are in port.
MEPG
6th October 2002
