Although Brunel had estimated the cost of building the ship at £500,000, Scott Russell offered a very low tender of £377,200: £275,200 for the hull, £60,000 for the screw engines and boilers, and £42,000 for the paddle engines and boilers.
Scott Russell even offered to reduce the tender to £258,000 if an order for a sister ship was placed at the same time.
Brunel accepted Scott Russell's tender in May 1853, without questioning it; Scott Russell was a highly skilled shipbuilder and Brunel would accept an estimate from such an esteemed colleague without question.

In early 1854 work could at last begin.
The first problem to arise was where the ship was to be built.
Scott Russell's contract stipulated that it was to be built in a dock, but Russell quoted a price of £8,000–£10,000 to build the necessary dock and so this part of the scheme was abandoned, partly due to the cost and also to the difficulty of finding a suitable site for the dock.
The idea of a normal stern first launch was also rejected because of the great length of the vessel, also because to provide the right launch angle the bow of the ship would have to be raised 40 feet (12 m) in the air.
Eventually it was decided to build the ship sideways to the river and use a mechanical slip designed by Brunel for the launch.
Later the mechanical design was dropped on the grounds of cost, although the sideways plan remained.

Having decided on a sideways launch, a suitable site had to be found, as Scott Russell's Millwall, London, yard was too small.
The adjacent yard belonging to David Napier was empty, available and suitable, so it was leased and a railway line constructed between the two yards for moving materials.
The site of the launch is still visible on the Isle of Dogs.
Part of the slipway has been preserved on the waterfront, while at low tide, more of the slipway can be seen on the Thames foreshore.
The remains of the slipways, and other structures associated with the launch of the SS Great Eastern, have recently been surveyed by the Thames Discovery Programme, a community project recording the archaeology of the Thames intertidal zone in London.

Great Eastern's keel was laid down on 1 May 1854.
The hull was an all-iron construction, a double hull of 19 mm (0.75 in) wrought iron in 0.86 metres (2 feet 10 inches) plates with ribs every 1.8 m (5.9 ft).
Internally, the hull was divided by two 107 m (351 ft) long, 18 m (59 ft) high, longitudinal bulkheads and further transverse bulkheads dividing the ship into nineteen compartments.
Great Eastern was the first ship to incorporate the double-skinned hull, a feature which would not be seen again in a ship for several decades, but which is now compulsory for reasons of safety.

She had sail, paddle and screw propulsion.
The paddle-wheels were 17 m (56 ft) in diameter and the four-bladed screw-propeller was 7.3 m (24 ft) across.
The power came from four steam engines for the paddles and an additional engine for the propeller.
Total power was estimated at 6 MW (8,000 hp).
The specific requirements of the Eastern Company also vindicated Brunel's initial concept of using both paddlewheels and a screw.
The Great Britain had a chain drive 'overdrive' gear so that the slow-turning marine steam engines of the day could drive a screw propeller of a suitably small diameter while making the required thrust.
This had proven troublesome and in his new ship Brunel resolved to use direct drive, requiring the much larger propeller.
To be effective this had to be fully submerged at all times, fixing the ship's minimum practical draught while using screw propulsion at around 7.62 m (25.0 ft).
Brunel designed the Great Eastern to have a maximum draught of 9.144 m (30.00 ft).
The Company required that the ship be able to dock at Calcutta, where navigation was restricted by the shallow Hooghly River which required a draught of no more than 7.0 m (23.0 ft).
Brunel calculated that the ship would be able to carry enough coal to steam from Calcutta to a British port while not exceeding that draught, while if the ship took on coal for the final
Although Brunel had estimated the cost of building the ship at £500,000, Scott Russell offered a very low tender of £377,200: £275,200 for the hull, £60,000 for the screw engines and boilers, and £42,000 for the paddle engines and boilers. Scott Russell even offered to reduce the tender to £258,000 if an order for a sister ship was placed at the same time. Brunel accepted Scott Russell's tender in May 1853, without questioning it; Scott Russell was a highly skilled shipbuilder and Brunel would accept an estimate from such an esteemed colleague without question.
In early 1854 work could at last begin. The first problem to arise was where the ship was to be built. Scott Russell's contract stipulated that it was to be built in a dock, but Russell quoted a price of £8,000–£10,000 to build the necessary dock and so this part of the scheme was abandoned, partly due to the cost and also to the difficulty of finding a suitable site for the dock. The idea of a normal stern first launch was also rejected because of the great length of the vessel, also because to provide the right launch angle the bow of the ship would have to be raised 40 feet (12 m) in the air. Eventually it was decided to build the ship sideways to the river and use a mechanical slip designed by Brunel for the launch. Later the mechanical design was dropped on the grounds of cost, although the sideways plan remained.
Having decided on a sideways launch, a suitable site had to be found, as Scott Russell's Millwall, London, yard was too small. The adjacent yard belonging to David Napier was empty, available and suitable, so it was leased and a railway line constructed between the two yards for moving materials. The site of the launch is still visible on the Isle of Dogs. Part of the slipway has been preserved on the waterfront, while at low tide, more of the slipway can be seen on the Thames foreshore. The remains of the slipways, and other structures associated with the launch of the SS Great Eastern, have recently been surveyed by the Thames Discovery Programme, a community project recording the archaeology of the Thames intertidal zone in London.
Great Eastern's keel was laid down on 1 May 1854. The hull was an all-iron construction, a double hull of 19 mm (0.75 in) wrought iron in 0.86 metres (2 feet 10 inches) plates with ribs every 1.8 m (5.9 ft). Internally, the hull was divided by two 107 m (351 ft) long, 18 m (59 ft) high, longitudinal bulkheads and further transverse bulkheads dividing the ship into nineteen compartments. Great Eastern was the first ship to incorporate the double-skinned hull, a feature which would not be seen again in a ship for several decades, but which is now compulsory for reasons of safety.
She had sail, paddle and screw propulsion. The paddle-wheels were 17 m (56 ft) in diameter and the four-bladed screw-propeller was 7.3 m (24 ft) across. The power came from four steam engines for the paddles and an additional engine for the propeller. Total power was estimated at 6 MW (8,000 hp). The specific requirements of the Eastern Company also vindicated Brunel's initial concept of using both paddlewheels and a screw. The Great Britain had a chain drive 'overdrive' gear so that the slow-turning marine steam engines of the day could drive a screw propeller of a suitably small diameter while making the required thrust. This had proven troublesome and in his new ship Brunel resolved to use direct drive, requiring the much larger propeller. To be effective this had to be fully submerged at all times, fixing the ship's minimum practical draught while using screw propulsion at around 7.62 m (25.0 ft). Brunel designed the Great Eastern to have a maximum draught of 9.144 m (30.00 ft). The Company required that the ship be able to dock at Calcutta, where navigation was restricted by the shallow Hooghly River which required a draught of no more than 7.0 m (23.0 ft). Brunel calculated that the ship would be able to carry enough coal to steam from Calcutta to a British port while not exceeding that draught, while if the ship took on coal for the final
SS Great Eastern