Who is "Shachen"?
Rashi: The neighbor of Eretz Yisrael.
Radak: One who dwells in Yerushalayim.
Malbim: One who dwells in the boat.
What is the significance of "Chalisi"?
Rashi: Do not say that evil came to you due to this nation (Yisrael). Their sin is pardoned!
Radak: This is like they said initially, we became ill and pained from many afflictions. They will not say so further. Refer to 33:24:3:4.
Malbim: When the ropes snap, and the boat is plundered, do not say 'I cannot stand against Ashur that comes against me.' They plunder only Arei Yehudah, but not the boat itself (Yerushalayim).
What do we learn from "Nesu Avon"?
Kesuvos 111a #1: Anyone who lives in Eretz Yisrael dwells without sin.
Kesuvos 111a #2: One who suffers intestinal sicknesses dwells without sin.
Rashi: Refer to 33:24:2:1.
Radak: Hashem will pardon their sin, due to Chizkiyah, who rebuked them and made them repent. Hashem did a great salvation for them.
Malbim: Hashem will pardon the sin of Anshei Yerushalayim, therefore it will not be destroyed.