![]() The chain is limited to a maximum of 50 metres. Choices are without any snubber, and with increasingly more elastic snubbers. As calculated by the AnchorChainCalculator App: 12 different scenarios, four each at anchor depths 3, 5 and 9 metres. IPhone and iPad version available in the Apple Store! Android version available in Google Play Store! A tutorial video can be found here.Īnd a free Lite version of this app with slightly reduced functionality you can try out online here. This app calculates, among other things, the minimally required anchor chain length and the associated anchor load as a function of a couple of vessel parameters as well as sea / weather conditions:Ī brief introduction to the App can be found in English, auf Deutsch, and en Français. I have published an app for iPhone, iPad as well as Android. elastic, snubber / bridle, or very elastic rope, if you are using a mix of rope and chain. Thus, folks who say that in strong wind the catenary is gone, anyway, implicitly also say you need to have a very good, i.e. This is when shock loads will not get dampened by the chain anymore and need to be dealt with differently (i.e. Once the chain is pulled completely bare-taught, the catenary is gone and no more energy can be stored. The importance of a catenary for the anchor chain lies in the fact that it is the catenary that allows the chain to store more energy. The same shape you can see with telephone or power lines running from one pole to another along the road side. ![]() You will have seen examples in parking lots, where a chain was perhaps used to rope off a certain section, or one parking space in particular. Catenary, what is this?Ĭatenary refers to the shape a chain assumes when it is hanging down between two points. Boxes in light grey provide additional reasoning and information, which is further expanded on further down on this web page. My attempt at giving an overview of the various advices given here when having to anchor in a severe storm. Obviously, one can and should pay out more chain than that, but it is important to know what the minimum is to maintain the maximum holding power of the anchor. The minimally required chain length is defined by the chain still pulling horizontally at the anchor, but rising to the water surface right at the anchor shank. The documents and sections further below work out diagrams for the MINIMALLY required anchor chain length as a function of the water depth, Y, at the position of the anchor, the weight per meter of the chain in water, m, the wind strength, and the swell, tailored for different vessel sizes. The models developed here will hopefully help you to have a better understanding of the physics of anchor chains and snubbers / bridles and to make the right choices. I ignore friction and any form of energy dissipation, as this will only work in my favour and not lead to any increase in the chain length required. On this web page I try to motivate my choice of the correct anchor chain and its length and how to deploy it based on a mathematical analysis of the main forces and energies involved when anchoring. If you are one of those folks that have little patience and want answers within minutes – as I occasionally come across on some sailor’s fora – then just stop reading right here and now! You are not my intended audience! You may still want to install my AnchorChainCalculator app on iPhone or Android, though, it is easy to use… □ Note: The content of this web page takes a while to read and digest. : Corrected version with regards to calculating the elasticity of the chain (up to version 19).) : now also including the contribution of the vessel moving in the wind field when calculating the effect of dynamic anchoring (version 22 and up). ( : The brief digests for different windage areas now also contain diagrams showing the effects of snubbers and bridles. See below Klicke auf das Bild, um den ausführlichen Text auf Deutsch zu öffnen.Ĭlick the picture to see the full paper on anchoring in German. Now also available English digests for catenary calculations for various vessel sizes.
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