Seamanship: Anchor Chain Calculator: calculate the optimum chain length via app - now also for anchor lines with chain lead
When it comes to the required length of the anchoring gear, rules of thumb such as five or seven times the water depth are often used. However, these estimates are incorrect, especially in shallow water, more information can be found here. The "Anchor Chain Calculator" app from physicist and long-distance sailor Mathias Wagner is much more accurate. It is available for Apple and Android devices and the latest version can calculate not only with a simple chain, but also with any combination of chain lead and anchor line. If the chain diameter is adjusted accordingly, a lead line can also be simulated. The weight of a five millimetre thick, ten metre long chain corresponds approximately to the ten metre long lead ballast of the usual anchor lines.
The app not only takes into account water depth and wind pressure, but also expected swell and swell movements. Estimates or calculated values can be used for more complicated parameters such as the yacht's windage. The same applies to the elasticity of an anchor drop. The app also provides answers to possible "what if" questions. This allows the skipper to prepare for situations such as falling gusts or increasing swell. The app also calculates the expected load on the anchor and the pull on the anchor line.
The app costs around eight euros; those who only anchor with a chain and shock absorber can also use the free web version: anchorchaincalculator.com. Further information and a detailed description of the app can be found on Mathias Wagner's website, www.trimaran-san.de.
