@jim said: The mesh in the first post isn't very clean - there are many edges that are not connected to anything, and many that do not actually intersect. You really need to get in close to find them, but they are there. It might explain some of the results of using some of the plug-ins. Is this sort of thing a use for TIG's manifold plug-in? All of the rail ( cline) profiles do not intersect( except some places at the ends) with the bulkheads and if one uses a cutting plane and tries to create them there are points that look obviously out of place. Trying to fill in with a bezier curve can be done but the hull then is not correct. Working with the orginal post model with out correcting the profiles and itersection will probably result in problems just getting worse IMHO.