Hi. My surface has an odd protruding line. Beacuse of this I can't properly loft using the edge and when creating a solid this leaves me with a naked edge. I tried to trim even split this from the surface. No luck, but then trimming is something else I will address here later. Thanks for looking into this surface problem.
This looks like it's a result of a trim operation gone wrong - the line you see is actually a part of the surface but it's very tiny - far below file tolerances. Using RebuildEdges on the surface cleans it up, but may also affect the other surface edges. The problem should probably not have happened in the first place, but Rhino isn't always able to figure out complex trims perfectly, and doesn't clean up some of the tiny errors even if they are too small to be seen.
One of the issues here here is your file tolerances are too loose - you are modeling in meters and your absolute tolerance is .01 (meters) which basically means you don't care about anything smaller than a centimeter. In this case the defect is about a millimeter... Trimming and joining are tolerance-based - sometimes when tolerances are too loose, these kinds of errors creep in easier.
If it was me, I would tighten up the file tolerances to .001 - it might help a bit. Even on a 15m boat, I would like to be able to hold tolerances locally to better than one centimeter.