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Author Topic:   HART on CHART
jimh posted 12-17-2014 11:08 AM ET (US)   Profile for jimh   Send Email to jimh  
My great friend David Hart sent me several digital camera photographs of his chart plotter screen that showed some interesting anomalies in digital charts.

First David pointed out the difference between the Lowrance internal charts on his ELITE 7 Chirp chart plotter in the region of the St. Mary's River, connecting Lake Superior to Lake Huron, and the Navionics GOLD coastal USA charts for that region.

In his first view, we see a track of his boat making an abrupt U-turn in what the chart shows as water free from hazards, as shown with the Lowrance chart:

Lowrance digital chart
Lowrance chart display in St. Mary's River

Next we see the Navioncs chart of the same region:

Navionics digital chart
Navionics chart display in St. Mary's River

Wow--now we see the need for the U-turn: there is a 6-foot shoal with a rock awash right in the boat's path.

The omission of this hazard from the Lowrance chart is a rather serious problem for safe navigation in the area. I'll turn it over to Dave for more explanation.

Hoosier posted 12-17-2014 12:52 PM ET (US)     Profile for Hoosier  Send Email to Hoosier     
In today’s digital world paper charts have all but disappeared, in fact NOAA has stopped printing them! So what do we do? We have to be damn careful. I found this out this past summer when I was out on the lower St. Mary’s River trolling with my new whizz-bang Lowrance Elite 7 CHIRP Sonar/Chartplotter. I was just off the down bound shipping channel by Pipe Island and had a couple of shallow lines out when I saw a rock awash.

What caused me to investigate this was I was using the Lowrance internal charts and noticed a rock awash right next to me in what was near navigable waters. It wasn’t on my plotter’s display even though I was zoomed in. It caused a bit of angst since this was a new chartplotter with up-to-date charts. I was so concerned I actually called the Coast Guard at the Soo to report the uncharted hazard.

I then loaded the Navionics Gold chip that I had purchased with the plotter and loaded the US Coastal file. Nothing else was changed, just the background map file. The difference is amazing. Anyone going through that area on plane could easily have left a lower unit on one of those hazards that Lowrance didn’t show.

This is the difference between the Lowrance built-in chart package and the Navionics Gold package that I got with my Elite 7 CHIRP chartplotter. This is the same place at the same zoom level, the only difference is the background chart being displayed by the plotter. Note that there is a huge difference.

Since I'll be taking this rig to Florida in March, this week, here at home, I went looking at other areas and they are all that bad. The internal Lowrance maps are not safe for navigation, hell they are not safe even for casual running around. I would not use them at all.

The Navionics Gold is an option that is available with Lowrance chartplotters. I got it because it has the charts for all of North America, including Canada, something we Great Lakes boaters really need to have. Most other chart packages used to cut off at the US-Canadian Border. The lesson in all this? Try before you buy. If at all possible, try out the chip on a demo plotter in Cabela’s, Bass Pro, West Marine, Marine Max, or your dealer. Look at an area you know and see if it has accurate information. Be aware, the Canadians haven’t resurveyed most of the Great Lakes in the past 100 years!

jimh posted 12-17-2014 01:31 PM ET (US)     Profile for jimh  Send Email to jimh     
Here is the NOAA vector chart for that region, sized to match Dave's images. The waypoint is at the crosshairs of the target lines in the other images.

Lowrance digital chart
Lowrance chart display in St. Mary's River

NOAA Chart
NOAA Chart of St. Mary's River

Navionics digital chart
Navionics chart display in St. Mary's River

NOAA seems to be aware of the rock and shoal. This is not the first omission of a hazard found in Lowrance's own charts. See an earlier discussion about variations in charts for Isle Royale for more examples.

fno posted 12-18-2014 12:27 AM ET (US)     Profile for fno  Send Email to fno     
Dave,Jim, I have to ask the question here and it may be a difference between Lowrance and Simrad. Are we talking about the Genesis packaged charts versus Navionics? I am using two Simrad NSS-8's on my boat in Florida and I am pleased with the detail provided by Genesis with the chart plotters. There are zones that I am aware of that without a chart plotter I know to avoid but they show them as well. I have yet to be surprised by a discrepancy. Maybe their adaptation of the cartography is better in my region, but that makes me wonder about the quality of the adaptation. The adaptation of paper charts may be the true culprit here. Given the fact that most if not all chart plotter manufacturers supply a disclaimer that their charts are not all knowing and suggest that we rely on NOAA charts for the real deal is something to think about. For what its worth, nothing is free in boating. If a chart is provided by the hardware company as part of the package vs. the $300 Navionics chart, who is more liable for accuracy? I have bent a prop or two and replaced a skeg over the years. Do I blame the chart plotter or myself? I do know that after I screwed up and went back to check the chart it was my fault most of the time. What I can attest to is the discrepancies you guys have made about the differences of detail when zooming in and out on a chart plotter. It has led me to a habit of zooming in and out while running in unfamiliar territories. At the end of the day it is up to the operator to decide what is safe or not while underway. It is common knowledge that most of the worlds sea floor is well mapped by our government and the military but once in a while a sub or ship hits bottom.
jimh posted 12-18-2014 09:36 AM ET (US)     Profile for jimh  Send Email to jimh     
The branding with "Genesis" is used by Lowrance to mean charts that are created from the user's data or from other users, often called crowd-sourced charts. The general brand name for the Lowrance-published charts is INSIGHT.

A significant difference between INSIGHT and a separate publisher's charts, like NAVIONICS or C-MAP, is in the scope of the charts. The INSIGHT charts usually are selected only in two scopes: all inland lakes or all coastal areas. The NAVIONICS charts are usually smaller in scope, such as just a portion of a coastal region or a portion of the Great Lakes. Also, I don't think Lowrance has charts for regions outside the USA, while the other publishers have a catalogue of charts for around the world.

In the USA we are greatly benefited by NOAA's attitude about their electronic charts: they are free! Getting free electronic charts from a government is not the norm in other countries. One has only to go as far aboard as Canada to find out that official government electronic charts are not provided for free. Canadian government electronic charts are quite expensive. Their vector charts are in packages that are $600 and only cover a portion of a region.

The NOAA electronic charts are great, but they typically only cover coastal areas. NOAA is not charting your local inland lake, and for a detailed chart of it you'll have to turn to someone else. If you are boating on coastal water or on the Great Lakes, NOAA electronic charts are excellent, but, for some reason, hardly any recreational marine chart plotters are able to use them. There does seem to be a bit of change in course on this, as I recall that a few recreational-grade marine chart plotters may now support using NOAA digital charts. (I'll have to research that topic more to get some definite information.)

I have the INSIGHT coastal and Great Lakes charts on my Lowrance chart plotter, and I find them very useful for regions where I don't have a better chart available. For the regions where I do most of my boating, I have a NAVIONICS chart, and I tend to use those charts in preference to the INSIGHT charts.

jimh posted 12-18-2014 10:03 AM ET (US)     Profile for jimh  Send Email to jimh     
With Lowrance, the INSIGHT charts are themselves an upgrade and an option from the base map that will be provided with the chart plotter. I can't show an example of the Lowrance base map because my plotter has the INSIGHT upgrade. When you pick the upgrade option, you don't get the base map data along with it.
Hoosier posted 12-18-2014 10:38 AM ET (US)     Profile for Hoosier  Send Email to Hoosier     
The point of this thread is "be damn careful". The Elite 7 came with the Lowrance base chart package and that was what I was using until I discovered how inadequate it was and loaded the Navionics Gold card. One point I want to add, those micro SD cards are a BAD idea on a boat, they are small and light, hard to grab, and easy to blow away. At least it is portable, I can move it between boats as needed.

To build on Jim's thought, what all the manufacturers should do now is provide the free NOAA vector charts as the base level preloaded charts and let the third party vendors provide all the "plus-up" things like marina info, 3D, satellite photos, etc.. I believe there are smartphone apps that can do that now, so extending that capability to a modern chartplotter isn't a technical stretch.

jimh posted 12-19-2014 10:44 AM ET (US)     Profile for jimh  Send Email to jimh     
I started a new thread about NOAA free charts and which devices can use them. See

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