On Fri, 27 Nov 2009 06:18:52 -0800 (PST), Roger Long
wrote:

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


Did they try to cut too close to G'3' ? That's one reason I'm wary of
vector charts. At least the NOAA raster charts have withstood the
test of time, and the rocks in Maine don't move around all that much.

Welcome back, BTW.