Theoretical hull lines and plate thickness

[MikeJohns]

As others have already said; the sensible approach (and the default) is to work to the inside of the plate for metal construction and no shipyard I have ever worked with has ever done differently.
I provide CAD files directly now and no paper drawings except to shipwrights on smaller projects. I seldom provide offsets now except to define curves. The classic lines drawing is redundant and the detail is in the individual Frame drawing.

[Alik]

We used to provide:
1. Lines plan of hull and cabin, as reference drawing to evaluate shapes
2. Loft drawing or cutting files with offset (direction of offset depends what is built - male plug or female temporary mold built in plywood);

or
1. Lines plan of hull and cabin, as reference drawing to evaluate shapes
2. Loft drawing or cutting files with offset for boats built in sandwich panels;

or
1. Lines plan of hull and cabin, as reference drawing to evaluate shapes
2. 3D files for CNC machining of plugs/molds, no offset

or
1. Lines plan of hull and cabin, as reference drawing to evaluate shapes
2. Cutting files for frames, panels etc. for steel and alu craft; there is no offset for frames.

And yes, requirement to provide table of offsets always make us confused. Last time we did it for a) Professional Boatbuilder design contest and b) Russian Maritime Register of Shipping required for check of hydrostatics/stability with their own software. Never did table of offsets for construction.

Sample of loft drawing, for wooden plug of cat hull: