Canada lake mapping

I have an hds gen 2 on my snowmobile with a navionics chip. I also have the navionics app on my iPhone and both show me that there is structure but neither unit puts me on the spot I’m trying to find. However, the mapping for Lake Winnipeg seems like complete fiction, like they took a guess on the depth contour. Any suggestions? Is there a better, more accurate setup for gps lake mapping in Canada (especially Winnipeg and LOTW, Whitefish Bay). My buddy’s garmin handheld unit was definitely more accurate on Whitefish Bay, but Lake Winnipeg wasn’t mapped at all.

There is a local company called AEM mapping. They have done a good portion of eastern Manitoba. They have a group of anglers that actually run lakes with mapping software. Maps are amazing.

As for big windy, it’s in the works, but it’s a massive undertaking. And that lake is a mean bitch in open water season.