Bluegrass and Loon

[Moveon]

You fish them more often than I do, but I have never noticed lakemaster being off by that much. If I am sitting on a ledge, maybe that will happen sometimes because of poor GPS signal at the time. But their charts are excellent, within 1-2 ft that I've noticed on Bluegrass and Loon. The difference would more than likely be a combination of bad GPS signal at the time that exceeds the 3 meter accuracy, water level offset not configured correctly for current water levels, depth offset not set right, etc. If you don't mind, next time you are out snap a screenshot of the area in question with GPS coordinates on screen and I will run the AC Live on it next time I'm there and take a screenshot of the difference.

Steve That sounds like a good plan to try to see what's going on. Do you know the shelf that goes out from the East Bank into the lake the farthest. This is the area South of the entrance to the "H" where the shallow water reaches out the farthest into the lake. It's about half way down the East Bank from the entrance to the "H" area. The "H" is the first Cove or bay on the right after you leave the launch ramp at the South End of the pit and head North.

The area drops off from around 5 or 7 ft into 20 then again it will drop down into about 35 to 40 ft of water. The ledge there is not straight but jagged and some areas of the ledge go out further into the lake than others. It's about Fifty feet to 100 ft out off the bank. And it's inline with the handicapped ramp and the main sign board by the porta-poti. The other line of sight used to be a cross up on the East Bank and some rocks along the shoreline. That should get you into the general area of the drop off I'm talking about.

I'm using the Humminbird 898 SI unit and the latest software from about 2015 on that unit. My GPS signals are taken from a elevated position above my engine at the rear of my boat near the transducer. I get accuracy readings of about 2 ft or 3 ft according to the screen readings. But they still could be off as just because the screen estimates the accuracy at 2ft that doesn't always mean it's true IMHO.

Anyway I'm off about 20 ft or so as I explained. now other areas the accuracy is much better as they may have been survived closer with more data points. Date point = a depth reading connected to a longitude and latitude reading. The closer the data points are together the better the map will be.

Loon is listed but if you look close at the list of lakes in IN the loon pit in Warrick county is not listed in bold print and it's name does NOT have a * at the end of the name which indicated that it was surveyed by Lakemaster in High Definition. I'm not sure what they call HD?

I was there watching the IDNR crew surveying Bluegrass in the area I'm talking about a while back. About 4 years or so and they were not making repeated treks across the lake close to each other. The girl doing the survey drove about 100 yards apart on each transit line across the lake on the South End where I could see her driving the boat from the Parking lot area by the Concrete Launch ramp on the South end of the lake. It was in March and it was a cold windy day and they appeared to be cold and in a hurry to finish up the survey. I took pictures of her and the boat and the guy that was with her. I also talked to here for a few minutes and asked her what she was doing. She explained what they were doing and that they would collect the data on a data logger ( computer and then take the data back to the office and make a map of the data. I learned to make Topo maps by hand using data points in my College Physical Geology class at USI back in the 1970. Drawing the contour lines of equal elevation around the data points took some experience to do. And it helped a lot if you had a lot of data points on the map showing the elevations of each point. Often one has to interpolate the data to determine where to draw the contour line between two different data points.

I'd definitely update the Lakemaster Great Lakes Card if I thought that they had done more surveys and collected a lot more data points. But I fear that they are just using the data that was collected by this girl that worked for IDNR.

I talked to the IDNR Director of Fish and Wildlife and he knew who she was. I know the director as we went to Purdue together and took some of the same classes together. We use to go out and drink beer together and spent a lot of time together back when I was in college. I don't see him very much anymore as he's up in Indy and I'm down here in Evansville. But we talk on the phone once in a while and that was when he told me the name of the girl that does all their lake surveys for them. She did the job but I am picky and wish that they could have collected more data points than they did. They do a quick job of each lake as they have a lot of lakes to record.

[JustinM]

Navionics maps are pretty accurate out there. I've never seen one off by 20 feet there

[Moveon]

Navionics maps are pretty accurate out there. I've never seen one off by 20 feet there

One kind of map Lake master actually does their own survey of the lake and then make the map. These will appear in bold print on their list of maps on their web site. The other are HD or high Defination maps that are shown with a "*" next to the name of the lake on their web site list of lakes for each state or area.

The area of inaccuracy is the South Eastern Shoreline. If you try to go parallel with that bank you will find out that the depth goes up very shallow and then drops back down again and repeats this pattern several times.

When you launch from the South ramp head over to the Eastern Bank about 50 yards out from the bank and head North along that Eastern Shoreline. In the summer months you can actually see the weeds in water less than 7 ft deep. It's like there is a series of fingers that come out off the bank for 50 to 75 yards that are shallow with deeper troughs in between several of the fingers. That was the impression I got in my mind the first time I went along that stretch of water. One of those shallow areas goes out a bit further into the middle of the lake and had a drop off at the end of that shallow shelf or what ever it is. I'd love to see the lake drained once and see the lake bottom and take a picture or two of the lake bottom while it was drained.

You would agree that if you only take 100 sample points the ma would be less accurate as compared to if the survey team took 10,000 survey points on this lake. That is what I'm talking about. The further apart the survey points are the more likely the map is to miss quick changing depths like the area that I described above. Think of the three blind men and the elephant story. The more sampling points you take on a lake the more accurate the map of the lake will be in all areas. In the area I describe the water depth can change from deeper to shallow relatively quickly in a stretch of 200 yards or so. IE the edge where the water drops off is not a straight edge. It's very irregular in shape. I'm trying to rack my brain and figure out how that happened. Remember this was a mining area and is man made for bringing coal out of the ground and the lake is mostly a big hole in the ground with deep drop offs (sides) on the Western side of the lake. They didn't really reclaim the area where the lakes are. They just let if fill in with water. That's why it's some 50 to 60 ft deep in the middle of the lake.

[SteveM4A1]

Steve That sounds like a good plan to try to see what's going on. Do you know the shelf that goes out from the East Bank into the lake the farthest. This is the area South of the entrance to the "H" where the shallow water reaches out the farthest into the lake. It's about half way down the East Bank from the entrance to the "H" area. The "H" is the first Cove or bay on the right after you leave the launch ramp at the South End of the pit and head North.

The area drops off from around 5 or 7 ft into 20 then again it will drop down into about 35 to 40 ft of water. The ledge there is not straight but jagged and some areas of the ledge go out further into the lake than others. It's about Fifty feet to 100 ft out off the bank. And it's inline with the handicapped ramp and the main sign board by the porta-poti. The other line of sight used to be a cross up on the East Bank and some rocks along the shoreline. That should get you into the general area of the drop off I'm talking about.

I'm using the Humminbird 898 SI unit and the latest software from about 2015 on that unit. My GPS signals are taken from a elevated position above my engine at the rear of my boat near the transducer. I get accuracy readings of about 2 ft or 3 ft according to the screen readings. But they still could be off as just because the screen estimates the accuracy at 2ft that doesn't always mean it's true IMHO.

Yes I know of the flat you are talking about. Which Lakemaster card do you have exactly? I know on both of my Great Lakes cards (versions 2 and 3), Bluegrass is a high definition lake, but it wasn't surveyed by Lakemaster, which is why it isn't a "Lakemaster High Definition Survey". Next time I am out on Bluegrass I will run Autochart Live on it to see if there is any difference from the Lakemaster chart and post a screenshot of the difference.

Navionics maps are pretty accurate out there. I've never seen one off by 20 feet there

Me either. You aren't generally going to get that much error with Navionics or Lakemaster. That is why I believe it is more than likely GPS related. I have GPS issues sometimes on Bluegrass/Loon/Otter, where my units show me over 100 ft away on land. It usually only happens for a couple seconds before it gets back on track.

[JustinM]

I've thought about doing one of the community edits out there. Just seems like a giant waste of time. Lol

[Moveon]

Yes I know of the flat you are talking about. Which Lakemaster card do you have exactly? I know on both of my Great Lakes cards (versions 2 and 3), Bluegrass is a high definition lake, but it wasn't surveyed by Lakemaster, which is why it isn't a "Lakemaster High Definition Survey". Next time I am out on Bluegrass I will run Autochart Live on it to see if there is any difference from the Lakemaster chart and post a screenshot of the difference.



Me either. You aren't generally going to get that much error with Navionics or Lakemaster. That is why I believe it is more than likely GPS related. I have GPS issues sometimes on Bluegrass/Loon/Otter, where my units show me over 100 ft away on land. It usually only happens for a couple seconds before it gets back on track.

I actually took up shooting about two years ago. It's so much easier to get everything ready to go. I store my boat in the garage but keep a lot of my shooting stuff on the boat. So to go fishing I have to remove all the shooting stuff off the boat and then get the boat out. Therefore I've not fished much these past two years.

Now If I were fishing more often I'd think about buying a new Depth Finder and adding Autochart Pro or something like that to the unit. The part of Bluegrass Pit that I'd like to survey is the Most Southern Part and expecially the Eastern Shoreline area to about half way out from that shoreline to the West bank. That flat area's edge is what I'd target with lots of sampling points so as not to miss any thing in that area.

BTW: I have the first edition of The Lakemaster card (Great Lakes Card) that included the lakes of Indiana.