The madness continues!

I have now, I think, have a pretty fair hull, not too many lumps ect. I managed to remove the 'starving horse' effect now. But try as I might, I cannot get the stern to attach. I try to make it from a solid, as suggested, but must be doing something else wrong, as I can't get it to fillet at all.

I chopped off the stern and tried adding a planar panel, but this still won't fully joint up. For some reason I have a crack that I can't close. Pulling my hair out again!!

All this is before I try to get it into a solid...

Sorry for being dense! I come to this as a modelmaker, not a computer wiz!