Heruka,
Perhaps mine was too strong a blamket statement because at times I have bought boats that were essentially intact but needed a fairly comprehensive list of work and still come out Okay at resale (if I included nothing in the equation for my fairly extensive committment of time).
I also agree with your statement that to a great extent, a 20 year old boat may need as much work as a 30 year old boat, except that, depending on the specific model, the hull of the 20 year old boat is likely to be better engineered and constructed, (i.e. have an internal framing system, resins and fabrics that were handled properly, better resin ratios etc.)and the systems are likely to be more up to date, (i.e. bigger battery boxes, tinned wire, breakers rather than fuses, regulation compliant main disconnects on the 110v system, low friction steering systems, ''odorsafe'' waste piping, modern diesel engine, proper propane system installation, modern
winches, spars and stoppers, etc.) and better aesthetics such as intact interior finishes (with the exception of upholstery which is near the end of its lifespan).
The other factor is the value of the finished boat. Again, dependent on model, the older boat''s price will always be limited by its obsolete naval architecture and its age. The newer boat will generally have a wider range of resale prices between an updated, mint condition model and one that is trashed. The cost of the restoration of a beater may be roughly the same (or slightly less) for the new vs older boat, but the higher range of value for the beater vs restored newer boat in restored condition may allow you to recoup the cost of restoration whereas it is generally nearly imposible to do that with an equal condition older beater.
That said, you are right that there are cases when the older boat does make sense. Tartans are a good case in point since thier initial build quality tended to be quite good, and, from a design standpoint, most of their models were pretty advanced for their day. Refresh my memory, what model Tartan did you restore?
Respectfully,
Jeff