The model isn’t a closed polysurface so this would need to be tackled first.
The input curves aren’t symmetric, their endpoints do not line up and some of the curves have duplicates… Overall a lot of problems…
Did you change tolerance to 0.01 on purpose? Well, I changed it back to 0.001 and fixed all your input curves. If you’re going to change the curves, you need to be more precise and make sure the end points match the surrounding curves or have clear overlaps.
I’ve used loft, sweep 1 and 2 to create a closed model.
The cutout side to side is done with a boolean subtraction. Note how the cutout surfaces have their normals. Instead of trying to match surface edges on the cutouts, I’d suggest to have overlapping geometry which will ensure your objects can be trimmed.
Shelling the hull to give a thickness is problematic due to the narrow and pointy surfaces. Your quick solution to get a closed offset polysurface is to rebuild the hull without the narrow surfaces and shell that. Delete the outside and subtract offsets of the side to side cutouts.
The two polysurfaces in the attached Rhino model join to a closed polysurface.
hull.3dm (2.3 MB)