Marine surveyors perform inspections of vessels of all types including pleasure craft, passenger vessels, tugboats, fishing boats, barges, dredges, oil rigs, ferries, cargo vessels and warships, as well as marine cargo, marine engines and facilities such as canals, drydocks, loading docks and more for the purpose of pre-purchase evaluation, insurance eligibility, insurance claim resolution and regulation compliance.
What is a Boat Survey / Yacht Survey?
marine surveys Basically, it is a detailed inspection of a boat, hopefully done by a qualified, diligent, intelligent and honest surveyor, for the purpose of determining its current condition and seaworthiness. In particular, to determine if the vessel is safe to use in conditions for which it was designed, and what maintenance and repairs are required, or are likely to be required in the near future.
Most buyers are not experienced enough, or mechanically inclined to a point where they can make an adequate evaluation on their own. Even those who are qualified benefit immensely from a second professional, cold and unbiased opinion.
Why Should You Get One?
The short answer is to stay alive, physically and financially. The open water can be a treacherous place, subject to the whims of weather and lady luck. It is no place for a deficient boat, especially one with an inexperienced owner and an inept crew (read first time boaters). And, as the old saying goes, a bad boat is a hole in the water that you pour money into. 
Buying a marine survey is buying peace of mind. It will give a better idea of exactly what you are getting into with your boat purchase, and help you learn what will be necessary to maintain the vessel in the future to keep you and your family safe, and your investment secure.
The longer answer is certain types and makes of boats have recurring problems or requirements. A good surveyor will be familiar with most models and be able to advise you on the long term suitability of your intended purchase and its equipment, particularly in relation to how and where you will be using it.
In addition, it is unlikely you will be able to secure insurance or financing without providing the insurance company or lender with an acceptable survey….. so you might as well make the survey a condition of purchase to begin with. 
Good luck and happy boating!
Don Robertson Webmaster
P.S. Many of the Marine Surveyors who have web pages featured on my Marine Surveyor Page have very detailed explanations about the different types of surveys and what exactly is entailed. Some even have advice about how to be sure the surveyor you hire is qualified. Check them out….. an educated buyer is an intelligent buyer!
Another good place to look is the web site for the Society of Accredited Marine Surveyors, they have their entire roster of over 1000 Marine Surveyors (both Accredited Surveyors and Surveyor Associates) published on the site, sorted geographically. Similarly The National Association of Marine Surveyors is another very reputable organization to use in looking for a marine surveyor Many of the surveyors listed on these sites have links to their own web sites where they publish information about their experience, their qualifications, and the type of work they normally do.