fleet angle

[derekleffew]

Rigging. Term used to describe the deviation of a line running over a sheave or drum from perpendicular to the axle.

From J.R. Clancy Reference - Stage & Rigging Glossary

The angle formed between the centerline of a sheave or drum and another sheave or fixed point.

http://www.wintech-winches.com/net_files/calculating_fleet_angle.htm

While some degree is tolerable with a sheave, and inevitable on a drum, too great of a fleet angle causes undue wear on components and adds excessive friction/drag to the system.