How do Jim and Huck escape after their raft breaks loose and floats away?

In the classic novel The Adventures of Huckleberry Finn by Mark Twain, Huck journeys down the Mississippi River with an escaped slave named Jim. Five days after they pass St. Louis, Missouri, they encounter a terrible storm bursting with thunder and lightning. In the flashes of lightning, Huck notices a steamboat that has run onto a rock. He persuades Jim to go over to it and explore, thinking that there might be something aboard worth pilfering. They tie their raft to the wrecked ship, and Huck goes to investigate voices that he hears.
It turns out that three men are in a stateroom. Two of them have tied up the third and are threatening to kill him. When Huck returns to Jim, he finds out that the raft has broken loose, and he decides to find the skiff that the men came in. For a moment it looks as if two of the men will escape in the skiff, but then they go back inside. Huck and Jim get in the skiff, and Huck cuts the line attaching it to the steamboat. They float downriver without using the oars until they are safely away. Then Jim takes the oars, and they search for their raft. When they find the errant raft, they hoist the skiff onto it. Eventually they sink the skiff and continue their journey on the raft.

In chapters 12 and 13, Huck and Jim discover a damaged steamboat that is slowly sinking. Curious, Huck asks Jim to tether their raft to the boat. When Huck climbs aboard, he sees three robbers: one tied up, one wanting to kill the tied-up robber, and the third suggesting they leave the man there to sink with the steamboat.
When Huck rejoins Jim, he is informed that their raft has untied and drifted down the river due to the storm. Huck and Jim then decide to look for the robbers' skiff. They find it, jump inside, and cut the rope to escape before the robbers make their way to it. By doing so, they not only escape but make sure the robbers won't get away.
Huck and Jim speedily float downstream in the skiff. Moments later, they find their raft and leave the skiff behind. However, Huck feels guilty leaving the robbers in the sinking boat, and he decides to inform a nearby ferry night-watchman about the steamboat.