The textile as strong as steel
The universal shackle does not exist, one must choose for a specific function. For example that for a 90°manoeuvre, a wide shackle for the mainsail, or a shackle for rope. We offer, as well as galvanized for mooring, forged stainless steel models. For each certified product we give you the maximum load point. This must be divided by 2.5 for the work load. The advantage of forged steel as opposed to moulded, is that it has a higher resistance, as well as deforming before breaking.
The base material for the shackles is stainless steel (forged, moulded or HR-High Resistance.) Galvanized steel is used often for mooring lines (see anchors.) It is less resistant than stainless steel and has a tendency to rust when the galvanizing is damaged. Bronze is reserved for traditional boats and decoration. Today there are textile shackles, these have two advantages: weight and strength. For example, a Dyneema strap of 8mm in diameter and a weight of 10 grammes, is given for 500kg. For the same strength a forged steel shackle must be 12mm and have a weight of 200grammes.
The manufacture of stainless steel shackles
Casting, consists of heating the metal (fusion,)and cooling it in the shape to be used. In forging, the metal is heated and pressurised in a matrix forming the hollow part of what is to be made. A moulded piece has an elasticity of almost zero. On a forged piece before rupture, there is elongation and deformation. Standard steel is 316L. One also finds HR shackles. In this case, the steel contains a small amount of carbon (0.07% max,)this increases the resistance to breaking, but diminishes it in the face of rust. As well as resistance, an 8 mm forged shackle has a breaking load of 2160 kg, an HR of 3520 kg.
The textile shackle
A fairly recent arrival is the textile shackle. Thanks to the Dyneema braid, seamanship may be improved in certain quarters. Very simply without any special knowledge, one can equip their boat. The Cousin kit for example, is composed of 10m of Dyneema and a hollow needle, may create 10 textile shackles (instructions supplied.) Dyneema is insensitive to UV, hydrocarbons, chafing and very tough and inelastic. It has all the characteristics necessary for use on a sailing vessel.