I love nothing more than teaching sailing and boating. When I teach navigation by paper charts, I always (used to) tell the student that "The chart is NEVER wrong" and you must figure out what mistake you've made.
I do recognize that there are some poorly charted areas in Alaska and areas of shifting coral in the Pacific, but in my waters, the charts are spot on.... or so I thought.
When Maptech brand charts first came out, I was immediately impressed. They are on waterproof paper, have some added extras, like ferry routes, on the charts, and have a wonderful contrast color scheme that makes them really easy to read. They also seem to be well thought out with regard to where they put their edges. ie you're not navigating on the crease very often, and they have a generous overlap when you use 2 of them, or turn a page in one of their books.
Imagine my suprise, years ago, when I'm navigating the narrow channel of buoys on the back side of Whidbey island and the buoys don't match my chart. The buoys are numbered, 8, 12, 14, 16, 16A....
16A???? What? The buoy in front of me says 18. Wait a minute... I've never seen a nun buoy with a number and a letter before.... I confirmed my position using a lot of different reference points before I decided that, in fact, the chart was wrong.
I called Maptech to tell them of their error. I was laughed off the phone on my first 2 tries. After getting laughed off the phone though, I actually did get a call back from their head cartographer. He was skeptical at first, but I told him to put his chart next to a NOAA chart and look at the buoy numbers and he wouldn't have to take my word for it. He agreed, the chart was wrong and newer versions are corrected.
Fast forward to a couple of weeks ago. My wife and I decide to cut through a group of small islands and shoals called The Wasp Islands in the San Juans. We'd been around them a million times and decided it was time to pick our route through.
My wife is an excellent chart navigator and was piloting and plotting our way through, when things went south. We finally stopped and drifted trying to make sense of the chart. It just DID NOT make sense.
After much discussion, "well could that be this island and that one over there actually be this other island?" I decided to get out 2 more charts of the area to compare. Sure enough, Maptech was wrong again!
This time they had all the islands in the right places, but TWO of the islands were green, as if they were shoals that are covered at high tide. One of these green shoals had a house on it and cliffs!