Roger Long
Senior Member
A couple of people are still checking it out. I’m not too familiar with the program so further investigation and comments welcome.
Navionics seems to have changed the displayed chart soundings so that they are corrected to the state of tide at time of viewing. Convenient maybe for the boater with minimum navigational proficiency that the program seems increasingly aimed at but a potentially dangerous trap. If you plan a route ahead of time (always good practice) at high tide, you could have a surprise if you arrive six hours later. How does auto routing know when you plan to leave? A friend who primarily uses the program has discovered that depths in places that don’t change, such as behind locks, have their depths changed according to the nearest tide station which may be on the other side of the lock.
If there is a notice somewhere that Garmin has changed the established nautical practice of chart soundings always being MMLW, it’s hidden enough that I haven’t seen it.
Navionics seems to have changed the displayed chart soundings so that they are corrected to the state of tide at time of viewing. Convenient maybe for the boater with minimum navigational proficiency that the program seems increasingly aimed at but a potentially dangerous trap. If you plan a route ahead of time (always good practice) at high tide, you could have a surprise if you arrive six hours later. How does auto routing know when you plan to leave? A friend who primarily uses the program has discovered that depths in places that don’t change, such as behind locks, have their depths changed according to the nearest tide station which may be on the other side of the lock.
If there is a notice somewhere that Garmin has changed the established nautical practice of chart soundings always being MMLW, it’s hidden enough that I haven’t seen it.