Rather than following generic and unspecific advice how much chain to pay out when at anchor, use this app to calculate the amount of chain needed for the anchor to have the best possible grip – safety tailored for your vessel!
Only too often does anchoring advice boil down to: Use a scope (i.e. ratio of chain length to water depth) of 3:1 in calm weather, and increase this to 5:1 or 7:1 as the wind picks up. This advice is independent of your vessel’s characteristics, independent of water depth, swell, or even the wind strength. So, is a scope of 7:1 still good enough for the storm tonight? Is the snubber / bridle good enough to do the job?
The Anchor Chain Calculator allows you to calculate the minimally required anchor chain length based on a number of vessel characteristics and sea / weather conditions. It tells you what load the anchor will have to bear, and when you are using a snubber / bridle, how much of the swell it absorbs, and how much it reduces the anchor load.
You can also restrict the chain length if you have to – perhaps because of nearby neighbours or obstacles – and get information how this restriction affects the anchor load and the angle at which the chain pulls at the anchor.