I've got a boat hull that I'm working on, and I created the model by using surface lofts. I used surface fills to close it in completely, and was able to get the whole thing to knit together successfully, if I dont try to create a solid model. However, if I check the box to attempt to create a solid model, it says it fails to knit surfaces.

I need the final part to be a solid model, and unfortunately I have very little surfacing experience. Most of what I have now is just from a large amount of trial and error.

I've attached a part file, iges & step file, in the hopes someone cna help. The file was created in SW2013.