I'm assuming it is a Bluewater trawler and not a Bluewater houseboat. You will find a link on this website for Bluewater trawler owners. We love the overall design of the boat-it's combination of handling and livability. The biggest concerns water ingress in any part of the decks/superstructure. These were not built with the best of plywood. Most, like ours, have rebuilt decks. Like so many other Taiwan boats, wiring was also lacking. We spent twice what we paid for her (and would have been 6x what we should have paid) as well as taking 2 years to rebuild her. We have ended up with a boat that we love and have immensely enjoyed over 15 years and thousands of engine hours of cruising in Alaska. Having done a lot of the work ourselves, we know the boat and all of its systems intimately. Get a survey!
Without knowing more about the boat and it's condition, engine hours, equipment, etc. and what has been done over the years to alleviate its weakness', it would be hard to put a price on it. It could be $5k or, at the extreme upper end $100k. If we were selling ours I would value it at $60k. All wiring, plumbing and heating systems were replaced 15 years ago. All new aluminum windows were installed-most double paned. All decks have been rebuilt. This is just a partial list of the original rebuild. In addition, in the past few years we installed a new 6kw Northern Lights generator, had the hull repainted with LPU and will be installing a new inverter with a new lithium house bank. Hope this helps.
PS. If you see our old boat Shangri La-a GB 50 that is based in Scappose-say "hi".
Tator