There is also another way to check this out. I load the GPS tracks
from my cruises into Google Earth as you can see here (click the image
it see the GE version):

http://www.rogerlongboats.com/2009September.htm

Going back over my trips I can see that, in Maine at least, there is
almost perfect correspondence between the Bluecharts and Google Earth.

Here is a bit of the shoreline of the southwestern tip of Newfoundland
traced in Bluecharts and then transferred to Google Earth. It's
clearly not as accurate as in Maine. However, I don't have the
detailed charts for Newfoundland unlocked and this is a trace from the
larger area chart that serves as the basemap. I would have unlock the
chartset for Newfoundland and redo it to see what the actual
correspondence is but it will give you an idea of what can be done.

http://www.rogerlongboats.com/images/GErock.jpg

I've found the Bluecharts generally very accurate around the coast of
Maine but on stunning error in a very well traveled channel right in
Portland Harbor came to light recently when the brand new fireboat
tore a shaft off and damaged most of its centerline.

Here is how Bluecharts shows a section of Whitehead Passage:

http://www.rogerlongboats.com/images...eadGarmin1.jpg

and here is how NOAA shows it on their most detailed chart:

http://www.rogerlongboats.com/images/Whitehead.jpg