Marine Surveys are performed for a number of reasons and the procedures for each varies to best suit your needs.
CORROSION SURVEY:
This is performed to determine a vessel’s level of cathodic protection, the bonding health and the presence of any destructive stray current leakages. An ultrasonic thickness measurement and insulation resistance test (megohm or megger test) may also be offered, upon completion of this testing, a written survey report describing the cause of corrosion and recommended repairs or upgrades can be provided.
ELECTRICAL SURVEY:
Electrical surveys are performed to assess the overall condition of a vessel’s electrical systems. This electrical surveys check for basic compliance with the electrical division of the Standards and Technical Information Reports for Small Craft published by the American Boat and Yacht Council, Inc. (ABYC) and the electrical chapters of NFPA 302 Pleasure and Commercial Motor Craft published by the National Fire Protection Association (NFPA) as well as safe, reliable and seaworthy electrical engineering design, installations, equipment and materials.
PRE-PURCHASE SURVEY:
This is the most comprehensive type of inspection, and is strongly advised when purchasing a new or used vessel. Condition and the overall operation of the vessel should be examined. This includes such items as structural integrity, out of water inspection, sea trial, electrical systems, propulsion system, fuel system, machinery, navigation, miscellaneous on board systems, cosmetic appearance, electronics, and overall maintenance.
INSURANCE SURVEY:
This inspection is performed so that the insurance 
company can determine whether or not the vessel is an acceptable risk. They are interested in structural integrity and safety for its intended use. Most insurance companies require a survey on older boats. They will also want to know the vessel fair market value.
APPRAISAL INSPECTION:
This inspection is performed to gather enough information to justify or determine the fair market value of the vessel. This is normally needed for financing, estate settlements, donations, and legal cases.
DAMAGE INSPECTION:
This is performed to assess the extent of damage, recommend repairs, estimate repair cost, and if requested, the probable cause.