Hi Rudl, also one way to kind of improve the model without fully rebuilding it is to make it into a solid by lofting some of the bottom pieces and joining those surfaces together, then scale it just in the x-axis direction to stretch it out a bit.

Then a new surface constructed using a sweep as I described above can be positioned like this:



And then Boolean difference can be used to cut the body with that new surface, and the outer solid pieces can be deleted, that will essentially remove the previous side surface and replace it with the new sweep one:



I've attached a 3DM model file that has that done to it, this version should fillet better now.

- Michael