Re:Deck

[MICHAEL KERR]

yes you can only extrude boundary edges, the red line of your wing is your boundary edge, once you extrude to your centre line you can lower your top (deck) surface to follow your wing curvature, you are giving your wings an upper surface. Once your hull has a deck you can mould the deck into any shape you like by raising and lowering control points, adding extra control points, add extra lines (as long as lines dont cross over each other) and turning your lines red (knuckle lines) or leave them gray (round curve)
Make a copy of your hull and experiment on it.

Mike