For the most part my surfaces are in good condition, I'm just starting to get some checking in the finish and in some areas some changes in coloration in the finish. There are some areas, like the entrance companionway ladder that show much more wear but that is solid wood and not the finish veneer used on the interior doors and such. I'm more concerned with conserving the "artwork"...On your surface prep: Is the surface in good condition and is it an oil-based finish like varnish or urethane? If it is, don't sand much. Just get the old finish clean, flat and smooth. You probably won't need more than one or two coats. Don't sand too much just achieve making the surface flat. Then roll and tip.
Now, as to what the original finish is, I don't know but I might be able to find out. The boat was built in 1984 in southern Spain and the original builder is still alive. I can ask him or one of his children. They have been answering folks questions. That's where I'll start.
That's a major concern - it's all custom veneer work and really lovely....On the other hand if you have a finish to remove be very careful not to go through veneer. Don't sand much!
dj