Blending surfaces

I am trying to blend two Polysurfaces and can’t figure out how.
Normally I would intersect them, create a pipe around the intersect curve and cut both surfaced to get offset edges to blend.
The problem here is that the curve is to tight or sharp and pipes don’t work properly.
Is there any other way to offset the curve on to the compound surfaces?

dear @user749 what s your (nick)name ?
you can _offsetSrf the orange Surface to trim the gray surface and vice-versa…
and if you post a file, it would be helpful
kind regards -tom

  1. Extract a curve from the sharp surface edge of the orange engine. Make an offset curve.

  2. Make an offset copy of the white (or grey?) wing and use it to split the engine and then delete the unnecessary piece. Delete or hide the offset surface.

  3. Use the offset curve that was made in step #1 and use it to split the upper portion of the wing. Delete the unnecessary piece.

  4. Use “Blend surface” to connect the split edges of both, the engine and the wing. You may need to adjust the handles of the blend surface to make it smoother.

The curve doesn’t project that great or I just suck at those things.
Figure it’s not worth the time to solve that.
I got a rather nice fillet from boolean the two parts but it’s just a surface and I cant get it into the solid which I need to substract from the form.
Thought it might be easier to fillet the edges on the negative form but that’s not working great either.

This is a stabilizer for a hydrofoil. Normally I wouldn’t bother with filleting because I would print a plug and ad the fillets with plasticine but this time I want to directly 3D print the molds.

That’s the mold. Figure I can print the middle part with 5mm wall thickness and sand the print to archive the fillets.

Thank you all.