The winch on the medium-sized ship was specifically designed for hauling heavy vessels.
As for Ghost-head Chang's treasure, a portion of it was hidden in a double-layered concrete fortress built underwater to completely seal out the seawater. Back when he kidnapped Nie Zhao, there had still been a dedicated passage leading straight to it.
Later, however, when Chen Ke and the others launched a forcible assault, Chang had been in such a rush to flee that he directly blasted the concrete fortress into collapse. Then, he packed a shipping container with the belongings he had left outside and hadn't yet managed to send in, and sent the whole thing straight to the bottom of the sea.
Chapter 323