Stuck @ King Asvalds Son Quest on Fastland - I can't find anything

[messiahgov]

Okay I got that quest and I have searched all over Fastland (finding any clue about the missing son of King Asvald, Riftland). I was in air, on land and on water with a ship. Checked all those wreckages (incl. small island which look like the right spot), talked to all (not so many) NPCs and so on...nothing at all. I'm stuck here and frustrated. I googled a bit, but there are no threads about that quest (no quest guides, no wiki etc.). Just a french comment, which mention the quest, but nothing more.

I think I missed something or the quest is bugged, because any other quest was okay (just this 1 mio. gold battle, which crash the game shortly before I win). I use 1.3.1.6250, if this makes any difference.