Rigging Block Redirect Resultant Load
Resultant force on a rigging block and its anchor when a line changes direction.
Example
You enter
- Line tension through the block (lb) 3000
- Direction change (deg, 180 = doubled back) 90
You get
- Resultant on the block / anchor 4243 lb
Checked against published worked examples from: ASME B30.26 / rigging statics.
Details, formula, and sources
ScopeResultant force on a rigging block and its anchor when a line changes direction (up to twice the line tension when doubled back). Size for the resultant, not the line tension.
Formula or tableresultant = 2 x line_tension x sin(direction_change / 2). A 180-degree turn doubles the line tension on the anchor.
Source and editionASME B30.26 and standard rigging statics by name; first-principles vector resultant.
Free accessThe vector-resultant statics are public. The block's rated capacity comes from the manufacturer.
What governsEstimate. Head rigger and manufacturer working-load-limit charts govern. Inspect every piece of hardware before the show.
API field namesline_tension_lb, direction_chg_deg, resultant_lb
- Resultant 2 x line tension x sin(direction change / 2)first-principles statics