Cargo ship: 3,000 tonnes of water pumped from stricken Solent vessel
Up to 3,000 tonnes of water is being pumped out of the hold of the cargo ship which ran aground in the Solent.
The Hoegh Osaka has been secured two miles (3.2km) east of the Bramble Bank sandbank from which it freed itself on Wednesday.
Salvors said they were confident a "thin film of oil" on the water could be contained within the ship.
A spokesman for owners Hoegh Autoliners said work could be slowed down by forecast bad weather.
The 51,000-tonne vehicle transporter "refloated" itself unexpectedly at 14:00 GMT due to the high tide.
It was towed two miles east of Bramble Bank, where it was grounded on Saturday, and is being held by tugs between Cowes and Lee-on-Solent.
It is currently being assessed by salvage company Svitzer and remains at a list of about 50 degrees.
Speaking at a press conference Hugh Shaw, the Secretary of State's representative for maritime salvage and intervention, said the ship "remained stable" in its new deeper-water location.
He said between 2,000 and 3,000 tonnes of water would have to be removed from the vessel's cargo hold.
"There is a thin film of oil on top of this water which has probably come from the cars when the vessel has gone over.
"I've got confidence the salvors can discharge the bulk of the water from sucking underneath the oil and that will leave us with a small quantity of oil on board the vessel."
He added the discharge would take up to 10 degrees off the list.
Moving water around within the ballast tanks of the ship would then be done to bring it upright and allow it to be returned to port, he explained.
He said the work would be a "slow process" which could take up to seven days.
The spokesman for Hoegh Autoliners earlier said divers would carry out a survey of the hull to inspect for damage, especially to the bilge keel, which stops the ship from rolling.
"The weather is due to get worse and certainly over the weekend it will be quite choppy so the work will be carried out very slowly and carefully," he said.
"The vessel is listing at 52 degrees and to get fairly cumbersome equipment down the stairwells, which are at a very strange angle, requires super-human capacity. You have to take it really, really slow."
The condition of the cargo will also be assessed to check if it has come loose.
Vessel Traffic Services for the Port of Southampton said the Hoegh Osaka's generators had now failed, turning off the on-board lighting that had previously illuminated the ship.
The Marine and Coastguard Agency said the vessel had "self-floated at high water" on Wednesday.
At a news conference on Tuesday, Bram Sperling of Svitzer, said there was some water inside because of a "small opening in the vessel" that had since been closed.
A refloat was the preferred option to avoid further damage to the ship from the sandbank.
Salvage experts from Svitzer boarded the ship on Monday and began carrying out an assessment to form a rescue plan.
The Singapore-registered transporter set sail for Germany at about 20:20 on Saturday, shortly before being deliberately run aground by the crew.
There were 1,400 cars on board, including 1,200 Jaguar and Land Rover vehicles and 65 Minis, as well as 105 JCB machines and 500 tonnes of fuel.
Two crew members out of 25 rescued by RNLI Lifeboats and the Solent Coastguard on Saturday suffered non-life threatening injuries.
Two senior officers and a pilot stayed on board before being taken ashore.