Presumably you have put down a deposit condition upon a survey. Normally if the survey uncovers faults that in total come to over 5% of the purchase value you can pull out and get your deposit back. Now you might be happy to proceed but in this case you should go back to the vendor and ask, as a starting point, for a reduction equal to the cost of full repair. The next point would be say a reduction of 75% of cost. The vendor may say, I will get it fixed and sell the boat to you for your offer price. In this case I would decline and ask for deposit, because the vendor will probably be inclined to get the work done as quickly and cheaply as possible.
Also talk to your surveyor see what he/she thinks.
One thing to be aware of is that faults that you have been made aware of prior to the survey cannot be used as 'bargaining chips' after the survey, as it is assumed you priced those in when making the offer. Not sure whether this applies. When were you given the 2016 survey, before or after your survey.
Brokers sometimes will offer an old survey (often after you've made an offer), I would never accept one, as anything mentioned on that old survey cannot be used to reduce the price if you've made your offer. This is in the small print of most agreements.
The membership association for owners of Dufour Yachts