Snatch

A sudden shock load caused when slack in a line is taken up abruptly.

An anchor, mooring or towing line can snatch when vessel movement alternately slackens and then jerks it tight. Inadequate scope, little elasticity, waves and poor lead can increase the load on the line, fittings and vessel.

In a separate verb use, to “snatch a turn” is to take a quick partial turn of a line around a cleat, bollard or post to gain temporary friction and control. Hands must remain clear because the line may tighten or render rapidly.