Hello Sofia,
I have a 1973 Dufour 35, and I’ve found it to be an excellent boat.
As I understand it, Hull Identification Numbers were introduced in the EU in 1998, and no Dufour 35 will have one.
https://www.boatshedsupport.com/article/90-hin-hull-identification-numbers
https://www.iso.org/standard/18059.html
Mine has been on Part 1 of the UK Ships register since it was new, and has never had a hull identification number listed in its registration. What my boat does have, though, is a rectangular metal plate at the aft end of the cockpit, behind the wheel and just below the emergency steering/tiller mounting (see not very good photo). This has various data about the vessel, including the year of manufacture and a number. Before 1998, manufacturers generally assigned numbers to production boats in the order they made them. I think mine is number 70-something. It was common on small cruising yachts of the 60s and 70s for this also to be the sail number.
I think there must be a solution to your problem, or no pre-1998 boat could ever be exported. In the UK, the Ship’s register people communicated entirely by email and were ver happy to answer questions. You only have to look at Dufour 35 to see it was made in the 70s, but if yours has the plate at the back of the cockpit, that should be ample proof that you don’t and can’t have a HIN. The broker who sold me mine was also very helpful, and the surveyor knew a lot about this stuff too.
I think it’s worth trying to navigate the bureaucracy here. There must be a solution for older boats (as there is for VAT – my boat also has no VAT receipt because VAT didn’t exist here when it was new). This can’t be the first time this has come up.
Anyway. Good luck. These are wonderful boats that will take good care of you if you take good care of them. Find a big open space to practice reversing in, because the prop-walk on them is terrible. This has its advantages – I can execute a perfect turn on the spot by putting the helm hard over to port and gently switching from forward to reverse and back again – but I haven’t yet figured out how to reverse under power out of a berth while turning to port. I’ve found it easier to simply walk the boat backwards with the helm hard over and then jump on at the last moment, calmly walk back to the wheel, straighten up, and drive away. If yours has a different engine/prop arrangement you may find things easier.
Best wishes,
Andy