Surveyor’s Opinion:  Even with new rebars set at the corners, having your land surveyed is not a guarantee that a Court of Law would agree.  As with all aspects of our legal system, a judge and jury can reach decisions that differ from the expected results.  Lawyers don’t guarantee that they will win your case, they give you an opinion about the likelihood of success.  A doctor doesn’t guarantee an operation will be a success.  Many even have you sign a waiver acknowledging possible problems.  The same is true with surveyors.  A professional land surveyor is obligated to perform sufficient research, measurements and deed analysis to render a professional opinion about your boundaries.   The survey plan shows that opinion, but it is not a guarantee.  To get a guarantee, you need to buy owner's title insurance WITHOUT the survey disclaimer that is common in most policies.  Some newer policies may include "Enhanced" coverage at a higher premium.  Be sure you know what your title insurance covers!

Deed Bearings:  A bearing is the angle from a north/south line usually Magnetic North.  Bearings in older deeds were assumed to be more accurate than distances or area because angles were usually measured by a surveyor while distances were often measured by inexperienced helpers.  But there are many ways for bearings to be wrong.  
          Compasses may have errors and it is not unusual for two surveyors to read a slightly different bearing for the same line even if they are using the same compass.  If they use different compasses years apart, discrepancies can be virtually assured.  Another error can be caused by magnetic attractions such as an iron deposit which might cause a compass to read incorrectly.  The direction of Magnetic North also changes over time (see declination below) and a one degree bearing change in a 1000’ line generates an offset error of 17.45 feet!  All these sources of error mean that even if your deed has two front corners and bearings to the back corners, a surveyor can not simply run out the lines with a compass without doing additional work.

Declination:  Is the angular difference from True North (near Polaris) to Magnetic North (compass).  Currently in Eastern Maine this difference is about 18 degrees west.  That means if you use a compass to find north, Polaris would be about 18 degrees to the right of your compass line.  But declination changes continuously and doesn’t always change in the same direction. This link will take you to a table showing historical declinations in Augusta, Maine.  In 1800 it was about ten degrees west (left of true north).  In 1840 it was about twelve and one half degrees west.  In 1940 it was about eighteen and one third degrees left.  But in 2000 it changed back to seventeen and one half degrees.  If your current deed is using a bearing that has been copied over and over again from an original deed in 1840 it may be off by five degrees and in a 1000 foot line, that error could generate a shift of over 85 feet.

Blazed Lines:   A blazed line is “A line of ax marks on trees that you can follow through the woods to find the corners of your land.”  Blazed lines DO NOT usually mark the precise boundary.  They are only intended to be close to the line.  The only way to be sure blazes are on a boundary is to survey the line with an EDM (not a compass) and most people are not willing to pay for that level of detail.
          In the past, the only way to complete a survey was by clearing a line of sight along the boundary.  The cleared lines eventually grew back, but the ax marks remained and could be followed to the corner.  But many property lines were never surveyed.  Someone might take a compass and follow the deed bearing toward the back corner.  If they missed the corner (because of the errors described above) they often just ran the reverse bearing back to the front and joined the two lines.  
          You should not measure a setback limit from a blaze to situate your new building at an exact offset.  The blazes are not intended to be exactly on your boundary.  I have seen 75 year old lines that were 60 feet off of a straight line between the endpoints.