Lowrance Maps

[agallant80]

The maps built in to my Eliete 7 are OK but they are a bit lacking in detail and well, they are off. They will get you to the channel markers but the map seams to have the channel at least 100 yards away. Its not the GPS thats off its the maps. My question is upgrading the maps worth it? It looks like I can upgrade to:
Nautics Insight Pro for $99
Nautics Insight HD for $149
Navionics Gold for $99
Navionics Platnum for $199

I am going to be boating on the ICW this summer and I am not too familiar with it. Anyone have any experience with these maps? If you could share your thoughts it would be appreciated.

 

[UncleWillie]

Re: Lowrance Maps

... Its not the GPS thats off, its the maps...

Actually, it is Both.
The GPS system has inherent inaccuracies and your GPS unit has additional.
At times 100 yards off is possible. Other times you will see less than 10.
The position of the satellites in orbit and the condition of the atmosphere all effect the accuracy.

When you are completely stopped; Tied securely or parked in the driveway;
Zoom in all the way and watch the "Bread Crumbs".
Over the course of a few minutes you will see the GPS wander randomly around a 50 yard area, sometime larger.
Your speed will vary from zero to ~3mph also.

Many of the charts produced for GPS were copied from the NOAA Paper charts.
Some have not been updated in decades, long before GPS existed.
The original positions were surveyed optically or via Loran and are close but not GPS accurate.

Do not attempt to navigate in limited visibility using GPS as your primary means.
As you have seen. It can get you close enough to eyeball the channel markers but your eyes are still primary.
It will get you close enough find a marina but not close enough to locate a particular slip.

The $200 charts are no more accurate than the $99 ones.
They just have prettier colors, more details and HD Photographs embedded.
The channel will still be in the same place.

 

[agallant80]

Re: Lowrance Maps

There are other things about the charts that came with the plotter that bother me. For example small islands and sand bars do not show up. If you look at the ICW in NC on the plotter you would think it is just a straight shot up the coast with nothing in your way. Now it does have the depth and channels marked but I would still like to know if there are any islands out there that I may run in to

 

[dingbat]

Re: Lowrance Maps

Two things to check. Make sure your map datums argee and make sure you have WAAS turned on if your unit supports it. WAAS will keep your position errors under 3M, 95% of the time.

Now familar with Lowrance GPS, but every other system I've worked with allowed you to adjust the amount of detail you see on the screen. I would check to make sure you have the level of detail set to "most"