We departed Digby, N.S. well before dawn in very thick fog. Visibility was about as bad as I've ever handled a boat in and I never would have gotten underway except for the need to be in the Saint John River before Hurricane Irene arrived.
I had set a course very close to the steep, bold shore so as to be out of any fishing vessel traffic. As we were approaching the shore, I looked down and saw that the route took us OVER the land. What the &^#^*(&$! I zoomed out the GPS display and the route was back over water. Just then, we saw the lights of a fishing pier and sheered off. The route did indeed go over solid land.
Looking at the charts later on both GPS chartplotters and the computer, I discovered this situation. Here is the chart zoomed in close with route lines drawn around the high and low water shorelines:
Now, here it is zoomed out one level:
And zoomed out to the scale where I was route planning in an area where the shore can be approached quite closely.
You would think that the zoomed out view would just be a less detailed image of the chart but not that the shore lines would be moving around. This is, in fact, the case everywhere else I have used these charts. There is something odd about the coding of this particular chart section as it only shows soundings and sufficient detail to navigate when zoomed in so closely that it's hard to use.
This is a rare defect in the Garmin Blue Charts but it's worth keeping in mind that this kind of thing could show up anywhere that you are not familiar with. It's another reason why you should use every available means to cross check and verify your position and routing with alternate navigation methods in critical situations.
Here is our actual track just one zoom level apart on the chartplotter display:
I had set a course very close to the steep, bold shore so as to be out of any fishing vessel traffic. As we were approaching the shore, I looked down and saw that the route took us OVER the land. What the &^#^*(&$! I zoomed out the GPS display and the route was back over water. Just then, we saw the lights of a fishing pier and sheered off. The route did indeed go over solid land.
Looking at the charts later on both GPS chartplotters and the computer, I discovered this situation. Here is the chart zoomed in close with route lines drawn around the high and low water shorelines:
Now, here it is zoomed out one level:
And zoomed out to the scale where I was route planning in an area where the shore can be approached quite closely.
You would think that the zoomed out view would just be a less detailed image of the chart but not that the shore lines would be moving around. This is, in fact, the case everywhere else I have used these charts. There is something odd about the coding of this particular chart section as it only shows soundings and sufficient detail to navigate when zoomed in so closely that it's hard to use.
This is a rare defect in the Garmin Blue Charts but it's worth keeping in mind that this kind of thing could show up anywhere that you are not familiar with. It's another reason why you should use every available means to cross check and verify your position and routing with alternate navigation methods in critical situations.
Here is our actual track just one zoom level apart on the chartplotter display:
