Perhaps it is a bit different north of the border. Down here, there is usually a clause about the sale being contingent upon the boat receiving an acceptable survey. However, the definition of an acceptable survey is not really spelled out. The tricky part is the deposit. If the buyer breaks the deal without good reason or claimed the survey was not acceptable for relatively insignificant reasons, like needing the hoses replaced, the seller may be able to keep the deposit.
From my perspective the wet rudder is marginal about the survey being unacceptable. When I purchased my boat, the survey found the rudder had split open (there is a longish story here, if you want to read it, go to
www.sv-secondstar.net). The seller arranged for the repair.
The broker can also work some magic here with the seller if the seller is a motivated seller. In some cases the broker can arrange for the repair to be completed at a discount to the seller, or reduce the broker commission to soften the blow. At this time of the year, the seller is also looking at another season of winter storage fees. That can be motivating.
Good luck.