Not sure what you mean by floating with the current...could you elaborate?
The set itself was secured and lowered into the water by use of hydraulic rams. The only time something floated loose from the set was at the end of the grand staircase flooding scene, part of the staircase became dislodged.
They should have filmed the GSC dislodging itself, since this is the theory that most people think how the GSC doesn't exist today. Anyway, they didn't have to do it purposely, since it dislodged itself. Or was it dislodged after they filmed, that made it unwise to film it? The GSC rising up would look a great spectacle!
On one of the many television specials that were broadcast on US television during the promotion of the 1997 movie, one of the cameras filming behind the scenes of the GSC flooding shot panned across the set, and jutting out of the whitewater deluge was the lower half of the boat-deck to A-deck staircase. Mention was made about the theory that portions of the staircase might have broken apart, and on the set, because the set stairs broke loose, they made a semi-conclusion/speculation that the real Titanic GSC might have done the same, broken apart, because of the lack of balustrades or columns.
However, if pieces of the GSC managed to rise beyond the forceful deluge of water pouring through the dome opening, which at the angle the ship was when this was occuring, perhaps most of what was being washed about might have headed toward the lounge corridor or lodged inside the foyer, yet. The staircase portions described as being spotted on the ocean surface after the sinking, in my opinion, likely were from the aft GSC, which was located where the tear occured when the ship broke apart.
Woodwork recovered from the ocean surface belonge dmostly to the aft GSC area, and FWIW, I believe the lounge piece could have been from the aft door leading to the corridor to the aft GSC.
And, no, the stair set pieces didn't rise up in some 'phoenix rising from the ashes' - it was destruction at work.
I also understand the GSC flooding scene was shot in one take, because of the level of destruction the set underwent to make the scene as realistic as possible, stair separation notwithstanding.
Your'e right! The suction makes the water pull up and down when the ship sinks. That creates small waves. And because the funnel fallin' down into the water, it makes the ship less heavier. So the bow lifts up.