You will need to download the free Humminbird PC program from Humminbird ... because HELIX will not directly recognize Nav data except in Humminbird proprietary format ...
https://www.humminbird.com/support/s...birdpc-v-4-6-1

Export the Waypoints from Lowrance in usr v3 or GPX and import into the Humminbird PC program ...

Then use the help manual under the About tab at the top of HBPC to manipulate the waypoints (if desired) and transfer the waypoints to a formatted SD Card (32gb or less) ...

Then insert the SD Card into the HELIX and select Yes when it asks if you want to upload Nav data from the SD Card ...

If the upload is successful there will be a white popup that says Nav data successfully uploaded Xxx waypoints ...

HELIX maximum waypoint capacity is 2750 waypoints ...

Rickie