You’re describing a normal purchase procedure: you agree to buy, and the seller agrees to sell at a given price, subject to the vessel passing your survey. You put down a deposit to show that you mean business, and get the boat surveyed at your cost. Online threads in France tend to relate horror stories about incompetent surveyors there, so be sure to find a good one. The advice is generally to avoid the surveyor that the listing agent puts forward. (The agent may be getting kickbacks or “finder’s fees” from that surveyor.) Instead, ask around at several boatyards who they would recommend. The Capitaineries at nearby ports may also have good suggestions for you. Take the top three and contact them to see what they will do for you. They will be in YOUR employ, working for YOU, so you need to feel that they know what they’re doing and will do a good job for you. A written report is a given, but will it be in boilerplate legalese that takes three pages to say nothing, or in sensible prose that tells you what you need to know in a simple paragraph? Be sure to be there for the survey so you can hear the surveyor’s comments about different issues and ask questions. YOU ARE PAYING for this, and a boat this size is a big investment. You want to avoid making an expensive mistake. For example on a boat this old, osmotic blisters can be a huge problem, or a minor one. The surveyor should be able to tell you how they might affect this boat, and a variety of possible fixes – along with ballpark pricing for the fixes. Take notes! Surveys are real learning experiences.
A survey should almost always find something that you were unaware of which needs fixing. This provides you the opportunity to decide that the “something” is sufficiently important for the boat to not pass your survey, and you decline to proceed with the purchase. You decide what is important to you. It does not have to be that the keel is falling off, or that the rudder is bent. A leaky hose in the head or scratches in the topside paint that you hadn’t noticed before could suffice. You then pay the surveyor, get your deposit back, and keep looking for a different boat. On the other hand, the “something” may be relatively minor, but may warrant renegotiating the price in order to balance out the cost of fixing it. A surveyor of one boat I was involved with found that the entire main bulkhead core had delaminated and rotted between two layers of fiberglass because of water intrusion. The sale still went through, but with a $5000 adjustment to allow for fixing the bulkhead. If you still like the boat despite the issues, renegotiate.
This boat has a deck-stepped mast, so I would pay close attention to the area around the mast step on the cabin top, looking for depressions and any crazing or cracking there. Likewise, the compression post in the cabin that supports the mast needs to be looked at carefully, along with its seating on the floors and pan of the bilge. Bon vent!