Winch Drum Fleet Angle

The sideways angle a wire rope makes running from a fixed lead sheave onto a winch drum.

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Example

You enter

You get

Details, formula, and sources

fleet_angle = atan(lateral_offset / lead_distance), where the offset is the sideways distance from the sheave's groove plane to where the rope lands (largest at the drum ends) and the lead is the perpendicular drum-to-sheave distance. A 6 in offset over a 240 in lead is atan(0.025) = 1.43 deg -- inside the guideline. The Wire Rope Users Manual / ANSI E1.6 guideline keeps it at or below 1.5 deg (grooved) / 2 deg (smooth); too large and the rope crushes earlier wraps or climbs the flange, too small (under ~0.5 deg) and it piles up. Lengthening the lead or centering the sheave lowers the angle. A design guideline; the equipment manufacturer governs.

fleet_angle = atan(lateral_offset / lead_distance), in degrees.

Winch drum fleet angle (the Wire Rope Users Manual; ANSI E1.6 entertainment rigging), by name; the drum, rope, and equipment manufacturer govern.

The atan fleet-angle geometry is a published wire-rope-practice relation; the offset and lead come from the drum and sheave layout.

Estimate. Head rigger and manufacturer working-load-limit charts govern. Inspect every piece of hardware before the show.

Field names used by the API: lateral_offset, lead_distance, fleet_angle_deg

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