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Mapping the West

Creating your own contour maps
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GPS and chart plotting sonars, along with detailed hydrographic maps have made locating great fishing structure so much easier.  But western anglers do not have the detailed maps (electronic or even paper) available as do our angling counterparts in the Midwest, south and east.  Companies like Navionics, Lakemaster and Lowrance offer few detailed maps for the western angler.  Of the available maps most have widely spaced contours, often greater than 20 feet, rather than the one foot contours on the popular lakes in those other areas.  The widely spaced contour maps are better than nothing but will not help you find that “spot on the spot” that can make the difference of a great day of fishing or no fish at all.

Left - Screenshot for Glendo; Right - One foot contours at Mille Lacs

Unfortunately for Western anglers the market for electronic maps is not large.  This makes it difficult for the major electronic map companies to justify spending money to create detailed maps.  There are small groups of anglers and individuals who have taken it upon themselves to make their own maps of their favorite fishing spots.  Professional software such as Global Mapper is expensive.  Hobbyists have been using less costly software such as Dr. Depth for mapping local lakes.  These programs make great maps, but do have significant learning curves.  Some, mostly those interested in computers, will find these programs interesting but many anglers will not want to take the time to learn them.

Lowrance recently introduced Insight Genesis for easily creating maps for the angler that wants good maps but really doesn’t want to spend a lot of time at it.  Lowrance has made making maps as simple as starting data logging when you get to the lake and uploading the data to Insight Genesis at the end of the day.  Lowrance sends an email in a few minutes to let you know your map is done.  Sonar logs from all who fish your lake and upload are combined to make even better maps, or you can mark your sonar logs private when you upload – no one (including Lowrance) will be able to see or use your data.

Sonar log creation can be done with any Lowrance HDS, LCX, Elite 7, Elite 5 or Elite 4 HDI unit.   Pop in an SD/MMC card (2 GB is plenty for a day of fishing) into an open slot, find the “log sonar” menu item, chose log to memory card option (not internal, as it will fill up fast and is inconvenient to transfer to your computer), and you are ready to start making maps.  Insight Genesis will create maps for any data collected where the speed is less than 20 miles per hour.  With other programs this high speed data needs to be removed manually, or a new log file must be started when going slow and logging stopped when ready to go fast.  If you have Structure Scan use the “log all channels” selection.  You should also make a reference waypoint somewhere on the lake and record the depth of the lake at that waypoint for the day.  Each time you return to the lake you should check that waypoint and record the depth.  You will want this information later.


Stop logging data at the end of your fishing day. Then when you get home, copy the log file to your computer.  I have a separate directory where I store my log files for each lake I fish just to keep it all straight.  Don’t forget to back up your data!

Upload your files to Insight Genesis.  The upload tool will ask you to select the files you wish to upload to Insight Genesis.  You’ll notice in in the screenshot below that there is an option to keep your data private.  If you wish to do so check that box before clicking on upload.  Uploading data may take a while depending on your connection speed and the size of your data logs. 

Once your map is complete you will get an email (see below) for each uploaded file letting you know your map is complete.  Just click on the link in the email and you will see your map.

Clicking the link takes you to the view below.  You can see the lake map overlay on an aerial photo of the area.

The red path above is the trail made while recording the data.  It can be turned off by clicking on “Track” above the map.

As you know reservoir levels move up and down throughout the year.  The depth you recorded at your reference waypoint (mentioned above) will be used to keep track of the depth of the lake for each recording.  Based on your reference waypoint you may want to add an offset to adjust for full pool of the lake.  Click on “Data Offset” to add any offset.

Insight Genesis will recalculate your map with the added offset and send you a new email link.  Once you have all your sonar logs adjusted for depth you can now create a map of the lake containing all your sonar logs.  Open one of your maps and use the “Merge Trips” tab.

Select the trips you wish to include by checking the box.  Insight Genesis will combine them into one map and send you another email to let you know your merged trip is complete.

Clicking on the link will take you to your completed map.

You will see the log trail on the completed map.  The above example shows closely spaced tracks.  This was a lake survey, not just a day of fishing.

Clicking on “Track” will turn off the sonar log trail and the completed lake map is shown with default 3 foot contours.  The contour interval and background shading can be changed by clicking “Contours.”  A dialog box will show you the selections available.


If you wish to change the contour interval select the new interval and the map will be redrawn with those contours.

Above is a zoomed area of the lake shown with one-foot contour intervals.  Vegetation or changes in bottom composition can also be great places to find fish.  Insight Genesis has the ability to show you those great fishing spots too.  Select the “Contours Only” dialog box to get choices of vegetation or composition to display on your map.


Bottom Hardness

Other interesting tools are provided in Insight Genesis.  You can see data such as water temperature, barometric pressure and air temperature on the day and time the sonar log was created.

You can also view sonar and Structure Scan data captured during the creation of your log file.  You can play back the data or use your cursor to follow the red track line.

Everything shown above can be done on your computer.  You can view your maps, make screenshots and print them.  All this is done free of charge.  If you wish to create maps that can be used on your Lowrance HDS Gen 2, HDS Gen 2 Touch, Elite 7 or Elite 5 HDI (others coming in the future), you can do so for an annual subscription.  As of this writing it is $99 for unlimited mapping.

Creating a map for your Lowrance is just a few clicks away.  Click on “Map Generation” to begin.  Select contour interval and any vegetation or composition overlay you want on your map.  You will be asked to select the directory for your map.

Run the application from that directory, select your SD/MMC card and the map will be created on the card.


Shown below is a typical base map for many of our Western reservoirs as displayed on your chart plotter.

Inserting the SD/MMC card containing our new map into the Lowrance chartplotter unit will automatically show contour lines created by Insight Genesis from the sonar logs.

Your map can also be displayed with a vegetation overlay.


Or a bottom composition overlay.


The examples shown above were created during a map survey.  These surveys take time and few anglers have the spare time to spend driving back and forth across a lake just to take data.  We would all rather be fishing.

The good news is that sonar logs can be created while fishing, especially when trolling.  Take a depth measurement at the reference waypoint you created for your favorite lake.  Then start logging data while you travel around the lake or fish.  Upload the data, adjust the depth offset and merge your latest data with any older files.  Eventually, you will have the interesting areas of the lake mapped.  Below is an example of several days of fishing.  Maybe next year I’ll get the rest of the lake done while fishing.  But even with what I have so far I have discovered some structure that I did not know existed.

Mapping lakes has become fairly easy.  Just remember to get the depth at a reference waypoint when you launch the boat and start your sonar log.  You can just go fishing while you collect data.  Save the data to your computer and upload to Insight Genesis when you have time.  In no time you’ll have a detailed map of your favorite lake.


© 2024 Dan Swanson
About the author, Dan Swanson:
Dan Swanson is a multi-species guide in Northern Colorado. He is an instructor and seminar speaker on fishing techniques with a specialty around the use of fishing electronics. Dan competes professionally in walleye tournaments around North America. He is on the Pro-Staff for Ranger Boats, Evinrude, Lowrance, St. Croix Rods and Costa Del Mar.