In order to insure proper wrapping on the drum and no undue wear of the wire rope, the fleet angle should be kept as small as practical. This is important to consider during the planning of a winch installation. Sheaves and drums should be placed so that the fleet angle will be equal on each side of the centerline of rope travel.
For a smooth drum a maximum fleet angle of 1-1/2 degrees is recommended. When the drum is grooved to suit the wire rope, the fleet angle should not exceed 2 degrees.
Example: Fleet Angle Calculation for 36" (914 mm) Chain Drive Barge Moving Winch
36" (914 mm) Chain Drive Moving Winch
Imperial
a = 18"
b = x (distance to be determined)
A° = 1.5° (minimum for a smooth drum)
tanA = a/b
tan 1.5° = 18"/x
.02619 = 18"/x
x = 18"/.02619
x ~ 688" (rounded up to next whole number)
x ~ 688" / 12 (convert to feet)
x ~ 58'
Metric
a = 457 mm
b = x (distance to be determined)
A° = 1.5° (minimum for a smooth drum)
tanA = a/b
tan 1.5° = 457 mm/x
.02619 = 457 mm/x
x = 457 mm/.02619
x ~ 17475 mm (rounded up to next whole number)
x ~ 17475 mm / 12 (convert to meters)
x ~ 18 m
