Shackle & carabiner

First, select based on connection dimensions: the pin diameter and internal dimensions must fit the fitting/block/eye and must not jam. Then select based on working load (WLL/SWL)—this must match the actual load condition (e.g., halyard, sheet, traveller, trim). As a rule of thumb: it’s better to allow for a sufficient safety margin rather than choosing something that’s “just barely adequate.” For safety-critical points (e.g., standing rigging/structural attachments), be particularly conservative in your sizing.

Shackles are the first choice for permanently loaded connections in the rig because they offer defined load capacity and high safety. Carabiners/clip hooks are useful when something is frequently hooked in and out (e.g., temporary points of attachment, safety lines, spinnaker/Code 0 handling)—here, a secure latch is important to prevent the clip from opening unintentionally. For high-load, permanent points of attachment, shackles are usually the more robust solution.

Stainless steel (A4/316) is the standard in the marine sector: robust, corrosion-resistant, and versatile. Aluminum saves weight but, when combined with stainless steel or carbon, can promote galvanic effects depending on the environment—so choose material combinations carefully. Composite materials can offer advantages in specific applications (weight/handling), but this always depends heavily on the specific product and load conditions. For most rigging connections, stainless steel is the safe, all-around choice.

Avoid “play”: Select shackle sizes so that connections fit snugly but do not jam. If necessary, use washers/straps or suitable fittings to prevent sharp edges from rubbing against the rope. Rubber rings/tape or targeted securing (e.g., wire securing on the shackle pin) help prevent rattling. It is also important to ensure that sheets and halyards are routed correctly through blocks and turn points.

For screw-bolt shackles, a bolt lock is recommended: a split pin, seizing wire, or a suitable retaining ring—depending on the model. In areas subject to vibration or impact, an unsecured bolt can come loose. Alternatively, there are self-locking shackle variants. Make sure that fasteners do not have sharp ends (risk of injury, chafing of sails).

Check regularly: Bolts/split pins/retainers, cracks/deformations, corrosion (especially in threads), as well as “worn-in” brackets and sharp edges. Check carabiners for spring function and secure closure. At points under heavy load (e.g., traveller, halyard deflectors), more frequent visual inspections are recommended—especially after strong winds or a regatta.