On January 6, there was a singular change in the behaviour of the ship. During the whole of the forenoon she moved gradually, yielding to the pressure at a rate of about an inch in four minutes. In the afternoon, however, she moved in short slides.
During this and the three following days her progress was about 10 feet each day. After this the ship, being to a considerable extent waterborne, was moved with greater ease, and on Tuesday, January 12, 20 feet was accomplished in less than four hours.
By Thursday, the 14th, the ship had traversed a distance of 197 feet at the forward cradle, and 207 feet at the after cradle. It was thought unwise to advance further till the coming spring-tides on the 19th of the month were past, lest an exceptionally high tide might come unexpectedly, and partially float her. As soon as the spring-tides had passed, she was moved on cautiously, a short distance at a time, and the depression of the ways was carefully observed. This was found to be inconsiderable, and the cradles were gradually pushed 25 feet off the ways. As the spring-tides came on, water was run into the ship, to prevent her from floating prematurely.
The upright struts of the cradle on the side next to the river were all removed, and the wedge-pieces had chains fastened to them, with the ends brought on deck; so that, if any of the wedge-pieces got jammed and did not come out when the ship floated, they might be hauled out by the chains.
The river tackle now consisted of two purchases at the bow and two at the stern. To keep the ship, when she floated, from being drifted by the tide or wind, chains were carried from the bow and stern to moorings, by which her movement up and down stream might be regulated. Four tugs were in attendance to tow the ship to her berth, and a floating fire-engine was also ready to pump water into her, should this be necessary owing to any sudden postponement of the launch.
Nothing now remained but to watch carefully for a suitable tide.
It was determined that, if the weather were favourable, the floating should be effected on Saturday, January 30. The tides had been below the average, and on the Friday matters did not look promising; the tides had continued low, and the weather was bad. A careful watch was kept on the tide, observations being taken every half hour, and plotted on a diagram so as to show at a glance the probable height to which it would rise.
The tides showed signs of improvement, and they commenced to pump water out of the ship on Friday night; but, as time went on, the weather did not mend, and the wind was blowing from the south-west against her broadside; therefore in the early morning Mr. Brunel, who was in person attending each turn of affairs, ordered water to be pumped in by the fire-engine. There was hard rain and strong wind; and telegrams which, according to arrangement, were being frequently sent from Liverpool and Plymouth, showed similar weather. This continued throughout the Saturday, and the tide was low; but, when it began to rise in the evening, it gave indications of being a very high one. As soon as the tide reached the Kingston valves, Mr. Brunel had water run into the ship. Although she rested uneasily on the cradles, she remained safely in her position.
In the evening the rain came down in torrents; nevertheless, after midnight the weather mended, and the wind went round to the north-east. As the telegraph gave the same report from Liverpool, Mr. Brunel, encouraged by every sign of fine weather, and having the good promise given by the high tide of the night before, determined early on the morning of Sunday, January 31, to float the ship on that day.
The pumps were immediately started to discharge the water from the ship. The bolts securing the wedge-pieces of the cradles were unfastened at daybreak, and the ship was then ready.