mark i had one done 2 yrs ago this month. if done correctly it will tell just about every detail as to construction, rig, mast, engine, shaft, strut if there is one, rudder, skeg, electrical, every thing that is on the boat should be checked, extras you name it. you should be there so the surveyor can talk to you and so you can see what he/she is doing. not to second guess them but if they were like our suveyor he explained alot about the construct details and what to watch out for later on. they earn their money if they are any good. my survey took 9 hrs for a 37' boat. i also had to set up a escrol account because we bought in late fall boat was hauled and engine could not be run and checked.