Pre-Purchase Surveys are typically undertaken by  buyers  prior to purchase, as a tool to aid in  establishing  whether  defects or  maintenance issues   exist in the vessel or its systems, and if so whether these are sufficiently serious as to compromise the viability of the vessel or affect its purchase price.  Conscientious sellers, aware that an unhappy buyer can be a liability,  also undertake this type of survey for guidance in putting the vessel in order prior to selling.