Rigging
Shackle selection by WLL (bow shackle, EN 13889 range)
- where
- WLL of the smallest suitable shackle in the G-4161 / EN 13889 range (t)
- load on the shackle (t)
- utilisation (%)
Explain this equation
Picks the smallest standard bow shackle whose WLL is at least the load it will carry. Use it when choosing shackles for sling legs, lifting lugs or master links.
T is the load the shackle carries: the leg tension for a shackle on one leg, or the full hook load at the top. WLL_s is the first rating in the standard range (0.33 t to 55 t) that is not below T. U shows how much of that rating you are using.
Shackles come in fixed sizes, so the choice is a look-up rather than a formula. The utilisation shows how much margin the chosen size leaves.
Sense check: a 3 t load needs the 3.25 t shackle, used at about 92%. A 10 t load needs the 12 t size.
Watch out: steps differ between makers and ranges, so only the WLL marked on the shackle counts. Side loading and spreading several slings across the bow reduce the rating.
Picks the smallest standard bow shackle whose WLL covers the load it will carry.
Enter your values to see the result.
Good to know
Range shown: Green Pin G-4161 standard bow shackles to EN 13889, WLL 0.33–55 t, minimum breaking load 6 × WLL; other makers’ steps are similar but not identical, so check the marked WLL. Use the leg tension (see the leg tension calculator) for a shackle on one sling leg, and the full hook load for a shackle at the master link. Shackles must be loaded in line through the pin and bow; side loading reduces the WLL according to the maker’s table. Check the pin fits the sling eye or lifting lug and the bow is wide enough for the number of slings.
Common mistake
Choosing a shackle on its pin diameter or body size alone. Sizes and WLLs differ between ranges and makers; only the marked WLL counts.
Limits
In-line loading at the stated temperature range only; no side load, no multiple slings spreading the bow. Dimensions converted from the catalogue’s inch sizes. For planning only: this does not replace a lift plan prepared by a competent person under LOLER 1998 (reg. 8) and BS 7121, and the manufacturer’s WLL markings, load charts and data always govern over this result.
Sources
- Van Beest Green Pin G-4161 standard bow shackle, catalogue page 2024 (EN 13889 / ISO 2415; WLL 0.33–55 t; MBL = 6 × WLL)
- The Lifting Operations and Lifting Equipment Regulations 1998 (SI 1998/2307), reg. 8: every lifting operation properly planned by a competent person, appropriately supervised and carried out safely
- HSE L113 Safe use of lifting equipment. Lifting Operations and Lifting Equipment Regulations 1998. Approved Code of Practice and guidance
Results are calculations from the published methods and figures shown, and depend on the data you enter. For planning and checking only. Scaffolds must be erected to NASC TG20 or a bespoke design by competent persons, and lifting operations planned under LOLER by a competent person. Never rely on these results instead of a design, a lift plan or manufacturer ratings.