Non-skid is a surface applied to the deck of a ship to increase the coefficient of friction and reduce the probability of footwear or vehicle tires sliding along a smooth wet surface. ^[1] When decks are painted for protection against wear and corrosion, non-skid may be formed by either mixing a granular material like sand into the paint prior to application, or by sprinkling dry sand onto a newly painted surface before the paint hardens by drying or curing. ^[2]

Examples

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  The portion of this submarine hull intended to be walked upon has been covered by non-skid identifiable by darker color.
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  Flight decks are entirely covered by non-skid to prevent aircraft from sliding overboard as the ship rolls.
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  The texture of this flight deck non-skid reveals the application strokes used to spread the mixture of paint and sand.

Sources