i think he just wanted to die as a hero, he wanted to die to let claire off the island. He din't want to die any other way i guess. About knowing it was not penny's boat i think he throught that if he lived and told everyone that it was not penny's boat then the losties will never get resuded.

__________________
Hurley: What about the B-O-D-Y-S?
Michael: What are spelling, man? Bodies?
Walt: B-O-D-I-E-S.

Hurley: Dude, you've got some Artz on you.

Bernard: I'm a dentist, not Rambo.
Rose: And don't forget that!