We've got a 1985 Vagabond 39, which although it was from a different designer it was built in the same yard (Bluewater Yacht Builders.)
While I cannot talk to the sailing attributes of the 42, I can offer a few of my discoveries about the build quality of the BYB yard. Of course, your mileage may vary.
Overall, we've been very happy with our 39. We've done the Loop in her, and it's taken us places we've enjoyed immensely.
While the rich teak interior is a major selling point, keep in mind that this was all done as a "one off." If you ever need to have interior repair
work done, then restoring it back to its original look means that someone's gonna spend a fair amount of time milling teak to get it back right.
The most important thing to do is to ensure that whoever you hire to do the survey knows his/her business.
Things to check for:
1. Soft decks. If the 42 was built with teak decks, then chances are good the screw holes have allowed water to penetrate into the plywood core. The coring of our decks was probably not marine grade ply (based on what I've pulled out of some soft spots), and therefore warrant close inspection.
tanks. Ours were steel, covered with a layer of fiberglass. While the theory was likely that the glass would serve as a barrier coat to protect the tanks, all it actually did was to trap water between the glass and steel. They finally failed last winter, and the replacement project is ongoing -- suffice it to say that it is a pretty major job.
3. Chain plates. While ours seem to be holding up well, it's really hard to tell with certainty. They are glassed into the hull, and buried behind cabinetry. Should they ever fail, replacement is gonna be a major expense.
4. Hull lay-up. While the hull is solid glass, we had issues with many areas of the roving that were resin starved. This allowed water to accumulate and become trapped within the hull. Again, not a complicated fix but it certainly was time consuming and a PITA.
5. Wiring. The wiring used was not tinned marine grade wire. Be on the look out for overall condition, which may indicate whether or not a complete rewiring project will be needed in the near future.
6. Stainless. As mentioned earlier, the stainless used in the yard was not 316L and be on the look out for crevice corrosion.
Anyway, just a few things to consider should you move towards purchasing.
All the best,