Crane Load Radius and Boom-Tip Height from Boom Geometry
Turns the boom-angle-indicator reading into the load RADIUS the load chart is indexed by: radius = boom-foot offset from the center pin + boom length x cos(angle); tip height = boom-foot height + boom length x sin(angle). A 30 ft boom at 60 degrees off a foot 4 ft out and 6 ft up puts the hook at a 19 ft radius and 32 ft tip height; lowering to 45 degrees swings it out to 25 ft. The inverse gives the angle for a target radius, acos((target - offset)/length), and flags a target beyond reach. RIGID-BOOM GEOMETRY ONLY -- boom deflection under load, rope stretch, and an out-of-level machine all INCREASE the real radius and cut capacity. The load chart, the load-moment indicator, and a qualified operator/lift director govern.
Formula and source
load_radius = boom_foot_offset + boom_length x cos(boom_angle); boom_tip_height = boom_foot_height + boom_length x sin(boom_angle); angle_for_target_radius = acos((target_radius - boom_foot_offset)/boom_length).
Crane boom geometry (load radius and tip height from boom length and angle), by name; the manufacturer's load chart and the load-moment indicator govern the rated capacity.
Audience
This tile is built for trades and the adjacent professions in the Rigging and Heavy Lift group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.
Related tools
Posture
Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.