what does non-slip mean?

What does non-slip mean?

Glasses with a non-slip ring on the underside do not slip when the ship moves slightly. What does that mean? A sailing boat in motion or a boat at anchor usually makes quite smooth movements and does not heel much. A non-slip glass is sufficient for this. Does it go out to sea or lay down at wind force 7 the motorboat driver with some wave the lever on the table, no glass is safe anymore, not even one with a magnetic base.

In the morning the boat sets off in the first warm rays of sunshine and it goes out to sea with a light breeze and moderate waves. We have breakfast and let us have one Pot of coffee tastes good, the ladies have their first sparkling wine in their hands and the children drink orange juice. A greeting motorboat driver rushes by and sends us its stern wave. Thanks to the non-slip glasses, everything stays on the table.