This is the toughest question of all. Some surveyors use a flat rate based on the length the boat, while others use an hourly rate. Either way, a pre-purchase survey will cost somewhere around $20 per foot, but it will be higher on large and complex (or older) boats. In some cases, it may be less. Remember, boats get large quickly—a boat that’s twice the length could have up to four times the surface area and eight times the volume. [links]