A 7-Ton Anchor Can't Hold a 76,000-Ton Ship in a Storm. It Was Never Meant To

A ship's anchor is not built to hold the ship in a storm, and the rules that anchors are built to say so in plain words. In this video, drawn step by step: how an anchor grips the seabed (like a plough, not like a weight), why the pull on it has to stay flat, how hundreds of metres of chain keep it flat and work as a spring, what the classification rules assume (sheltered water, 25 m/s of wind, no waves), and what happened on the night of 7-8 June 2007, when 57 ships were anchored off Newcastle, Australia, and a gale came in. All drawings are schematic and not to scale. Two figures are our own arithmetic from the report's numbers: the chain for one anchor (12 shackles x about 3.8 t = about 45 t) and the ratio of the anchor's weight to the ship's deadweight (about 1 : 10,000). Watch next: How the Biggest Oil Tanker Ever Built Stopped (It Took 9 km). If this was worth your time, a like and a subscription help the channel. And tell us in the comments: what should we take apart next? Chapters 0:00 Not built for a storm 0:54 The plan 1:08 1. How an anchor grips 2:21 2. The chain 4:05 3. What the rulebook says 5:49 4. One night off Newcastle 7:41 What holds a ship in a storm 8:11 Three takeaways Sources International Association of Classification Societies, Unified Requirement A1, Anchoring equipment, Rev.7 (2020): https://ww2.eagle.org/content/dam/eag... Australian Transport Safety Bureau, Marine Occurrence Investigation No. 243: grounding of Pasha Bulker, Nobbys Beach, 8 June 2007 (copy read; the report is published on atsb.gov.au): https://maritimesafetyinnovationlab.o... DNV, Anchor losses are on a negative trend: how to improve (technical news, 2021): https://www.dnv.com/news/2021/anchor-... All animations are original; diagrams are simplified and not to scale.