Working backwards from "what does Hoban's hat have to do with anything/everything" *ahem*
...
It was Chef with his pointy knife. There was no time to put dishes away so he had to pocket the huge blade. It accidentally jabbed Hoban toward the very end of the storm near the crates falling overboard (Hoban is seen standing next to Chef) at 6 when the storm was most rocky and they lost almost all of their supplies. We can only hope Hoban is hanging on for dear life on a floating crate, rather than lying dead at the bottom of the sea. *Sniff.*
The reason Chef stole the knife? He hated Hoban's hat and wanted to carve it to bits. He was near Hoban the most, probably stalking him for his hat, but didn't even have the heart to mug him when he heard about how Hoban was affected by Linae's comments. *Awwwwwww.*
At first I thought Anshu's motives were most suspicious and his story most consistent, but I can't figure out if it is Chef or Anshu that is lying now. Chef's stories seem to have more holes in it than probably Hoban's hat does now. *Chuckles.*
Kentari, I also agree is suspicious because he is least suspicious in a way. However I think his story is to point out to us the fact he noticed Chef taking a knife from the weapons storeroom.
I don't think Linae has anything to hide, since she is apparently very forthright, insistent, and consistent about her sheer dislike for Hoban. If she had any mal-intent, she would have slipped up or come out with it intentionally.
The reason Anshu claims Chef doesn't know what was bothering Hoban was because Chef just talked to him calmly (while secretly coveting his hat) and figured Hoban would be alright from then on.
If the curve on the "nav map" indicates the curve at the end of the "grid map" (reasoning the X on the nav on the other side of the line is where they went off course after the storm), extrapolating crudely:
G19 - "Someone" had to mark their place after the storm, indicating their re-route to Krawk Island.
G14 - If Hoban was seen up until almost the of the storm (Linae is next to him at the wheel last thing in her story, resentfully working side-by-side with Hoban) he must have fallen off shortly thereafter but before the next morning when anyone noticed he was gone (whomever marked G19 and I22).
Laugh if you will, it is the best I could come up with (for now).