The conventional working scope is 5–7× water depth (measured at the hawsepipe) for chain in calm conditions, increasing to 7–10× in heavy weather and 10–12× for storm or hurricane anchorage. The greater the scope, the flatter the catenary, and the less vertical pull is applied to the anchor — increasing holding power. Wire rope (rare on commercial vessels) requires roughly twice the scope of chain because it does not contribute weight to the catenary.

Swing circle is the maximum distance the stern can sweep around the anchor. It equals the chain veered + the vessel's length overall, plus a small allowance for chain catenary lift. A 250 m vessel with 8 shackles (220 m) of chain in 30 m water has a swing circle of roughly 470 m radius. Always check the swing circle clears all charted hazards and adjacent vessels at every wind direction.

Standard length: 1 shackle = 27.432 metres (15 fathoms = 90 ft). UK Royal Navy uses 12.5 fathoms (~22.86 m). Each shackle is colour-coded with paint marks on the links — typically a red link, white links, or numbered tags so the bridge knows how much chain has been veered.

No. Compute scope using the maximum expected water depth at the anchorage (high water + tidal range + sea state surge). If you anchor at low water with a 5× scope, that scope shrinks to 3× at high water — likely insufficient holding.