Koliver...you said you used an Evergreen Atlas which used CHS chart 3310.
I checked the CHS site and chart 3310 has been replaced by chart 3313. Maybe the reef in question is on the current chart?
http://www.charts.gc.ca/charts-carte.../index-eng.asp
Also, could this be a classic case where the fellow who went aground didn't "zoom in" on his electronic chart, and if he had zoomed in it would have shown more bottom detail?
Still trying to understand...