Lift Planning — Dynamic / Snatch Factor
Dynamic / Snatch Factor for engineered lift planning.
Snatching a load — hoisting into slack slings at speed — multiplies the static weight by this factor; at 0.3 m/s into a stiff bridle it brushes 1.45×. Offshore lifting codes (DNV) write DAF into every lift for exactly this physics. The cure costs nothing: take the slack out at creep speed first.
Formula
Note: Rigging and crane decisions are life-safety critical. This calculator is a planning aid — the load chart, sling tags, site lift plan and a qualified lift director govern every real lift.
Dynamic / Snatch Factor for engineered lift planning. A free crane load, wind & rigging safety tool — no sign-up, no upload, instant results in your browser.
About Lift Planning — Dynamic / Snatch Factor
Lift Planning — Dynamic / Snatch Factor computes the governing relationship DAF ≈ 1 + v/√(g·δ) — energy method for sudden load pickup live as you type. Snatching a load — hoisting into slack slings at speed — multiplies the static weight by this factor; at 0.3 m/s into a stiff bridle it brushes 1.45×. Offshore lifting codes (DNV) write DAF into every lift for exactly this physics. The cure costs nothing: take the slack out at creep speed first. Defaults are pre-filled with realistic values for this exact scenario, and the worked example substitutes your numbers step by step so the math is never a black box.
How to use Lift Planning — Dynamic / Snatch Factor
- 1Enter your values — Static load, Hoist speed at pickup, System stretch at load (rope+sling) (sensible defaults are pre-filled).
- 2Read the live results: Dynamic amplification, Peak line load.
- 3Check the "with your numbers" line to see DAF ≈ 1 + v/√(g·δ) — energy method for sudden load pickup substituted step by step.
- 4Adjust inputs until the scenario matches yours, then copy or share the result.
Why use Lift Planning — Dynamic / Snatch Factor?
- ✓Instant, free and private — every calculation runs client-side in your browser; nothing is uploaded
- ✓Built on the stated formula DAF ≈ 1 + v/√(g·δ) — energy method for sudden load pickup with authoritative sources cited on the page (ASME B30.5/B30.9/B30.20 — Cranes, slings and below-the-hook devices; OSHA 29 CFR 1926 Subpart CC — Cranes & derricks in construction; DNV-ST-N001 — Marine operations (DAF methodology))
- ✓Snatching a load — hoisting into slack slings at speed — multiplies the static weight by this factor; at 0.3 m/s into a stiff bridle it brushes 1.45×.
- ✓SI ⇄ Imperial toggle converts your inputs in place, so you can work in the units your drawings use
Frequently asked questions
What formula does the lift planning — dynamic / snatch factor use?+
It evaluates DAF ≈ 1 + v/√(g·δ) — energy method for sudden load pickup, exactly as published. Sources: ASME B30.5/B30.9/B30.20 — Cranes, slings and below-the-hook devices; OSHA 29 CFR 1926 Subpart CC — Cranes & derricks in construction; DNV-ST-N001 — Marine operations (DAF methodology). The substituted worked example on the page lets you verify every step against the textbook.
How should I read the result — and how far can I trust it?+
Snatching a load — hoisting into slack slings at speed — multiplies the static weight by this factor; at 0.3 m/s into a stiff bridle it brushes 1.45×. Rigging and crane decisions are life-safety critical. This calculator is a planning aid — the load chart, sling tags, site lift plan and a qualified lift director govern every real lift.
When is this calculator the right tool for the job?+
Dynamic / Snatch Factor for engineered lift planning. A free crane load, wind & rigging safety tool. Offshore lifting codes (DNV) write DAF into every lift for exactly this physics. For neighbouring scenarios, the related tools below cover the same engine with different presets.
Does it support both metric and imperial units?+
Yes — the SI ⇄ Imperial toggle converts the values already in the fields, preserving the physical quantity, so you can flip mid-calculation without re-entering anything.
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