Max Redirect Angle for a Block WLL
The largest direction change a block or anchor of a rated WLL can turn a line without the resultant exceeding the rating.
Example
You enter
- Line tension through the block (lb) 3000
- Block / anchor rated WLL (lb) 5000
You get
- Max direction change 112.885
- Resultant at that angle 5000 lb
Details, formula, and sources
angle = 2 x asin( WLL / (2 x line tension) ). A 3,000 lb line through a 5,000 lb block can turn up to 112.9 degrees; if the WLL is at least twice the line tension, any turn up to 180 degrees is within rating. Answers 'how far can I turn it' instead of the resultant from a set angle. Keep margin for shock; the qualified rigger and the tags govern.
max_direction_change = 2 x asin( block_wll / (2 x line_tension) ), the inverse of resultant = 2 x line_tension x sin(angle / 2); solvable only when WLL < 2 x line_tension, else any turn up to 180 degrees is within rating.
ASME B30.26 and standard rigging statics by name; first-principles vector resultant, solved for the angle.
The vector-resultant statics are public. The block's rated capacity comes from the manufacturer.
Estimate. Head rigger and manufacturer working-load-limit charts govern. Inspect every piece of hardware before the show.
Field names used by the API: line_tension_lb, block_wll_lb, max_angle_deg, resultant_at_max_lb
- Max angle 2 x asin( WLL / (2 x line tension) ), capped at 180 degrees when WLL >= 2 x line tensionfirst-principles statics