I have created a loft weight project but I am having difficulty creating the curved upper surface using the objects curves. I tried a loft and a mesh but I don't understand enough about how to create them or proper use of these surfacing techniques to apply them to my object. It has a base curve, a profile curve and 2 section curves. Currently I have created a solid from the base curve and the profile curve but that creates a blocky looking object instead of the object I want that uses the section curves as well.

I have attached the file, could someone show me or suggest how I should proceed to get the object I desire?

Thanks in advance,
Jay Abbott

I have added some of the source images I used to create the curves.