To make the best possible C-MAP Genesis* custom contour map of your favorite lake, pond, reservoir creek arm or river section, drive your boat pretty slowly, make shore-to-shore up-and-back trips spaced pretty closely together, and record small sonar logs with the correct settings dialed in on your Lowrance, Simrad or B&G GPS/chartplotter. Mapping is really based on your objectives-better maps at slower speeds and closer boat paths.
Following are all the details in a handy Best Practices Guide you can print, put in a Ziploc bag, and store in your boat.
* Formerly known as “Insight Genesis”
Logging speed
Recommended Speed –10 mph or less on lakes, reservoirs and rivers for all three layers (1-foot contours, submerged vegetation and bottom-hardness)
Maximum Speeds for Desired Outputs:
- Just 1-foot Contours – Less than 19.5 mph
- Contours, vegetation, and hardness – Less than 9.5 mph
Recommended boat path
To create the best custom contour map with C-MAP Genesis — be it of an entire lake, a reservoir creek arm or a section of a river — first parallel the entire shoreline of your interest area, driving slowly with about two or three boat-lengths between you and the shore (provided the water is deep enough to do so). Then continue paralleling the shoreline in concentric “circles” (see images below), re-positioning the boat closer to the middle of the waterbody with each complete circuit. Enable your Lowrance’s track-display feature to monitor the spacing between each trip around. The closer you space your tracks, the more detail your complete map will include. For atypically shaped waterbodies and/or very large waterbodies with numerous bays and/or creek arms, you can break up the total acreage into sections and drive concentric circles in each section (see images below).
Another approach effective for mapping some waterbodies is the “mow the lawn” method in which you slowly drive your boat while making shore-to-shore, up-and-back tracks across the entire area you seek to map. Some refer to this process as “mowing the lawn.” Complete your survey trip by driving a full circuit of the area as close to the shore as water depth will allow (see image below).
For the best results on most bodies of water, you can space out your up-and-back tracks at maximum 150 feet (a little less than 50 meters) apart. You might, however, want to space your tracks closer together. The tighter your spacing, the more accurate your map’s depiction of fish-holding bottom structure will be.
On ponds or other smaller and/or shallower bodies of water, you’ll get better results by spacing your tracks closer together. Follow these recommendations:
- 5 acres or smaller – 15 feet (5 meters)
- 6 to 10 acres – 30 feet (about 10 meters)
- 11 to 20 acres – 45 feet (about 15 meters)
- 21 to 30 acres – 60 feet (about 20 meters)
- 30 acres and larger – 150 feet (about meters)
To assist with track spacing, and to view your progress on the water, use your split screen – with your chart on one side, and your sonar display on the other – and set your chart to show your track/trail.
Want to make smaller files for quicker uploads? Read this article.
Map-as-you-go option
You don’t have to survey an waterbody all at once in the manner described above (although those methods will give you the best results, the fastest). Another way to use C-MAP Genesis is to record your sonar data every time you hit the water to fish. Eventually, you will build up a detailed contour map of your best spots visit over time, without additional time or effort. If there’s a particular area you want to ensure you have immediate full coverage of, however, follow the survey tips above.
To see a demonstration of the best practices for making custom C-MAP Genesis maps, watch the video below. Note: At the time the video was produced, C-MAP Genesis was called “Insight Genesis,” but the methods described still apply following the name change. (Article continues below video player)
Recommended and required settings
These settings on your Lowrance unit will result in the best custom contour, vegetation, and bottom-hardness maps:
- Fishing Mode – Shallow Water
- Ping Rate – 15 pps
- Range – Auto (Default). This is critical for optimal contours, bottom hardness, and vegetation detection
- Frequency of Traditional Sonar – 200 KHz or “High CHIRP” (Required)
- Frequency of StructureScan (if present) – 455 KHz
- Enable WAAS Differential Correction on GPS — For directions, click this link WAAS Differential Correction for a downloadable PDF.
Want step-by-step instructions to follow to dial in these settings? Click this link Insight Genesis Recommended Settings — Lowrance for a downloadable PDF.
Recording Sonar
- We recommend carrying or storing two 8 GB SD cards.
- We recommend logging no longer than one hour per file.
- Do not split both 83 & 200 kHz frequencies, and avoid toggling between screens and adjusting settings while recording data
For step-by-step instructions to follow to begin and stop recording a sonar log, click this link Insight Genesis Recommended Settings — Lowrance for a downloadable PDF.
Transducer placement
Failing to install your transducer correctly can interfere with your sonar signal, preventing collection of accurate data. For Lowrance’s transducer-installation tips, click this link: Transducer Placement Tips
Current software
Visit this website to ensure your Lowrance unit is running the most up-to-date software: http://www.lowrance.com/en-US/Software-Updates/
C-MAP Fishing 