A lot of
Black Ice around this season....ie
Clear Ice that you can SEE through... LOOK at the cracks. How DEEP are they. That's the way we judged the thickness back in the day. Ice boaters NEVER carried an Ice Drill.

FOUR Inches of black ice is Plenty.. for walking ..or ice boating.
PS: Think of it this way: ICE Floats. You are walking on a SLAB of "FLOATING" ..Ice.
In the pictures below......NOTICE we are Spread Out.
Sorry the pictures are slightly OFF Clarity. They were "Scanned" from 40 year old 35mm Slides. The Originals were Perfect. I have an
HP ScanJet 4050 Flat Bed Scanner. This Anomaly
Really Annoys Me.

Nb