Unfortunately that wasn't all your expert witness was interested in, including matters clearly beyond his understanding and experience. Your disagreement with Björkman notwithstanding, you agree with him in the question of the ship's purported buoyancy. You first reported his conclusions without citation. When asked where those conclusions came from you revealed you had copied them from Anders Björkman, whom you said you took as possibly some sort of expert. You had no idea whether he was an expert when you cited him as one, and you admitted at the time you were unable to determine the validity of any of those claims on your own.
Now your position has evolved. Somehow you still maintain that the ship sank extraordinarily quickly but you're unable to cite any authority beyond Björkman (or "Because I say so") to support this, and you are trying to tell us Björkman plays no role in your argument. You didn't know at the time whether he was a reliable expert, but now you're either sure that he is or are adamant that it doesn't matter whether he is or not because ideas are all that matters.