auto chart issues

[jkirch]

I am fairly new to auto chart so I am probably missing something obvious . Here is my situation. I have mapped a number of spots on a certain lake . They came out fine . When I add new data to the existing map the contour lines don't match up . I think I have a time consuming solution but just haven't done it yet . My solution is each time I get new data I would have to remake the entire map so all the data past and present would be configured at once . I am the furthest thing from a computer genius there is so I might be staring at the answer right in front of me . Any help is much appreciated . On a side note I don't see any of the pros mentioning auto chart. I would think with all the time they spend idling around these days such a program would be very helpful .

[Bob B]

What Autochart are you using? Are you compensating for water level changes?

[jkirch]

I am using auto chart pro . The lake I am mapping has a spillway and I have made sure I have done the sonar recordings while the lake is right at full or real close to it .

[Wayne P.]

I am using auto chart pro . The lake I am mapping has a spillway and I have made sure I have done the sonar recordings while the lake is right at full or real close to it .

Do you have a GPS antenna where the transducer is so the depth and location is in the same place?

[Bob B]

It is important to have a method to not the relative water level each time you are mapping ..... there are some very good tutorials in the autochart forum on here..... http://www.bbcboards.net/showthread.php?t=508722 .... or you can purchase the training set from Lake Images which is very good. The 3 DVD set is very good .... https://www.lakeimagestraining.com/

[jkirch]

I have two boats that share a 998si . The gps puck is mounted to the ram mount and gets transferred with the unit to each boat . Each time I have done sonar recordings I have removed the puck from the mount and sip tied it directly above the transducer . It seems to me that when a map is generated it "makes up" depth data off to each side of the boat . When I map a steep drop first it maps it correctly because I idled directly over that drop . The next time I map near that steep drop I might idle on the deeper side that has little depth change . When that data is generated into a map the over lapping areas that were "made up " don't match the previously mapped portions . I may have just restated my original post but I just wanted to give a little more info .Bob B I think I know what you are referring to for the relative water levels . The boat ramp at this specific lake isverry near the spill way so I can see the water level based on the amount of concrete showing . In years past I have actually taken a level and measured the lake level during drought years. During the times I have mapped on this lake the levels were less than six inches different and more likely less than 3. I have looked at some of the tutorials on here and there is a lot of good info . I am in the beginning stages of doing this so I have much to learn . One other thing about the "made up " data is when I idle within ten feet of the bank the map will show there might be 30-50 of distance before there is any bank . It will show up as a long extended flat when I can spit on the bank which I was idling by . I am in the process of making a new lake out line through google earth . This might resolve the problem .

[Wayne P.]

I have two boats that share a 998si . The gps puck is mounted to the ram mount and gets transferred with the unit to each boat . Each time I have done sonar recordings I have removed the puck from the mount and sip tied it directly above the transducer . It seems to me that when a map is generated it "makes up" depth data off to each side of the boat . When I map a steep drop first it maps it correctly because I idled directly over that drop . The next time I map near that steep drop I might idle on the deeper side that has little depth change . When that data is generated into a map the over lapping areas that were "made up " don't match the previously mapped portions . I may have just restated my original post but I just wanted to give a little more info .Bob B I think I know what you are referring to for the relative water levels . The boat ramp at this specific lake isverry near the spill way so I can see the water level based on the amount of concrete showing . In years past I have actually taken a level and measured the lake level during drought years. During the times I have mapped on this lake the levels were less than six inches different and more likely less than 3. I have looked at some of the tutorials on here and there is a lot of good info . I am in the beginning stages of doing this so I have much to learn . One other thing about the "made up " data is when I idle within ten feet of the bank the map will show there might be 30-50 of distance before there is any bank . It will show up as a long extended flat when I can spit on the bank which I was idling by . I am in the process of making a new lake out line through google earth . This might resolve the problem .

The only accurate data generated is what is directly below the transducer/GPS antenna. The software creates a very wide contour line (fake)(interpolation) that you have to blend in with many passes to get an accurate contour map created.

[jkirch]

I make my passes every 50 feet or less most of the time . I keep the zoom level set at 100 and base my grid pattern on that . I understand the fakeness of the program . How do I get accurate mapping if each time I go out recording I am then overlapping on existing good data . My plan is to load each and every sonar recording each time I update the map . I think this should eliminate most of the fake data . I have yet to do this so when it is done I will let you know .

[Bob B]

Every time you map a given area.....the more accurate the map will get since the interpolated data will slowly be replaced with actual data.

The only things I can think that would cause that to be otherwise would be if the GPS antenna is not correctly located over the transducer or the depth offset isn't correct when bringing the data into Autochart.

[Wayne P.]

This is an area I did with Navionics Sonar Charts. It does the same thing as Auto Chart, Auto Chart Pro, and Auto Chart Live.

Note the waypoint numbers for the chart curser.

This is the original contour map for this location and is not even close to being accurate. Interpolation created the stuff between recording passes.



I knew that was wrong so this is the Google Earth track for a correction recording:



This is the fixed contour mapping:

[jkirch]

I have added a google earth shoreline and added all my data at once to remake my map. This seems to have solve the problem. All the contour lines now match up . It is a little more of a hassle to load all the at once instead of just the new stuff. Now the only issue I have is that any mapping I have done before adding the new shoreline is still showing up on land . My new recordings are all contained within the new boundaries . Is there a way to erase or edit the existing map on the zlc ? I don't want to screw up my card so if there is any trickery in doing it I will just leave it alone . I will make a shoreline first on any new lakes I plan to map to avoid this in the future.