How to close complex geometry

I’ve got the following geometry:
and I struggle to close the top. The surface should have at least a continuity of g2 and follow the top curve of course. The trailing edge (sharp edge at the back) is not of concern as we trim that off later anyway. Is there an elegant way to do this?Curves.3dm (388.1 KB)

Is there a reason for the zero thickness trailing edge?

Your curves are pretty ratty too. They should be far simpler with fewer points.
The busy isocurves in your surfaces were a visual clue that your curves should be simplified and cleaned up.

@Stratosfear the zero thickness trailing edge is still present in this model because we trim it off later anyway. Feel free to trim it off yourself if it makes it easier to create the surface
@John_Brock We import the curves from another program, which doesn’t let us control the amount of control points. Reducing the amount of control points in Rhino is possible of course, but it is really import the curve stays the same shape as much as possible. What’s the best approach to achieve this?

Replacing your curves with simpler, more efficient curves would be dictated by your manufacturing process, materials used, and use. Then you can determine how far your cleaned up curves and resulting surfaces can pull away from your imported curves.

This is one way I would handle this form. I had to rebuild the surfaces. A lot of point editing to make things flow as well.

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It looks good, thank you! What approach did you use? And is it necessary to use a lot of point editing? I will have to draw a lot of these, so a fast, robust way of doing it would be very nice

The compound curvature of the primary surfaces makes this a total pain. Starting with Bezier main surfaces is critical. Then use split at isocurve with shrink on to to section them up for the blends. I use this approach to cap wing tips for CFD. I really struggled with all that experience to get an acceptable result with this. I also use VSR shape to point edit and evaluate surface continuity. I would try to find an acceptable single surface (rapid ship hull) method for this.