Snap Back and Mooring Deck Safety
Why painted snap-back zones were abandoned, the whole-deck doctrine that replaced them, the IMO position, and designing the hazard out of the mooring deck.
Snap back is the recoil of a mooring line that parts under tension, releasing the elastic energy stored along its length. It is among the most lethal routine hazards on a ship, and the guidance on managing it reversed direction in the current generation of industry publications.
The full article will cover why painted snap-back zones were abandoned: the trajectory of a parted line depends on its configuration, its elasticity and where it fails, cannot be bounded reliably, and a painted boundary creates false confidence in the deck outside it. OCIMF MEG4 and the Code of Safe Working Practices both dissuade the practice, the fourth edition of Effective Mooring removed the concept, and IMO now frames mooring areas as potential snap-back zones to be signed as such.
It will also cover what replaced the paint: designing the hazard out through line and tail selection, lead geometry that avoids turns, keeping personnel clear during tensioning, remote-release fittings, and automated mooring systems that remove people from the deck altogether.