I N S T R U C T I O N S H E E T
Black Magic Footblocks
N15W24983 Bluemound Rd., Pewaukee, WI 53072-4974 USA
Tel: 262-691-3320, Fax: 262-701-5780 • Web: www.harken.com, Email: harken@harken.com
WARNING! Strictly follow all instructions to avoid an accident,
damage to your vessel, personal injury or death.
See www.harken.com/manuals for additional safety information.
Angle of
deflection
Load factor
Angle of
deflection
Load factor
Angle of
deflection
Load factor
30°
52%
90°
141%
150°
193%
45°
76%
105°
159%
160°
197%
60°
100%
120°
173%
180°
200%
75°
122%
135°
185%
—
—
Block load increases when the line turns at a greater angle. Block loads
double when the line turns 180 degrees. See example below. Select blocks
carefully.
Block Loading vs Angle of Deflection
Example shows single
footblock with a sheet
load of 5000 lb (2268kg)
8650 lb
(3923kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
10000 lb
(4535kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
3800 lb
(1723kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
7000 lb
(3175kg)
5000 lb
(2268kg)
I N S T R U C T I O N S H E E T
Black Magic Footblocks
N15W24983 Bluemound Rd., Pewaukee, WI 53072-4974 USA
Tel: 262-691-3320, Fax: 262-701-5780 • Web: www.harken.com, Email: harken@harken.com
WARNING! Strictly follow all instructions to avoid an accident,
damage to your vessel, personal injury or death.
See www.harken.com/manuals for additional safety information.
Angle of
deflection
Load factor
Angle of
deflection
Load factor
Angle of
deflection
Load factor
30°
52%
90°
141%
150°
193%
45°
76%
105°
159%
160°
197%
60°
100%
120°
173%
180°
200%
75°
122%
135°
185%
—
—
Block load increases when the line turns at a greater angle. Block loads
double when the line turns 180 degrees. See example below. Select blocks
carefully.
Block Loading vs Angle of Deflection
Example shows single
footblock with a sheet
load of 5000 lb (2268kg)
8650 lb
(3923kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
10000 lb
(4535kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
3800 lb
(1723kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
7000 lb
(3175kg)
5000 lb
(2268kg)
I N S T R U C T I O N S H E E T
Black Magic Footblocks
N15W24983 Bluemound Rd., Pewaukee, WI 53072-4974 USA
Tel: 262-691-3320, Fax: 262-701-5780 • Web: www.harken.com, Email: harken@harken.com
WARNING! Strictly follow all instructions to avoid an accident,
damage to your vessel, personal injury or death.
See www.harken.com/manuals for additional safety information.
Angle of
deflection
Load factor
Angle of
deflection
Load factor
Angle of
deflection
Load factor
30°
52%
90°
141%
150°
193%
45°
76%
105°
159%
160°
197%
60°
100%
120°
173%
180°
200%
75°
122%
135°
185%
—
—
Block load increases when the line turns at a greater angle. Block loads
double when the line turns 180 degrees. See example below. Select blocks
carefully.
Block Loading vs Angle of Deflection
Example shows single
footblock with a sheet
load of 5000 lb (2268kg)
8650 lb
(3923kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
10000 lb
(4535kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
3800 lb
(1723kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
7000 lb
(3175kg)
5000 lb
(2268kg)
I N S T R U C T I O N S H E E T
Black Magic Footblocks
N15W24983 Bluemound Rd., Pewaukee, WI 53072-4974 USA
Tel: 262-691-3320, Fax: 262-701-5780 • Web: www.harken.com, Email: harken@harken.com
WARNING! Strictly follow all instructions to avoid an accident,
damage to your vessel, personal injury or death.
See www.harken.com/manuals for additional safety information.
Angle of
deflection
Load factor
Angle of
deflection
Load factor
Angle of
deflection
Load factor
30°
52%
90°
141%
150°
193%
45°
76%
105°
159%
160°
197%
60°
100%
120°
173%
180°
200%
75°
122%
135°
185%
—
—
Block load increases when the line turns at a greater angle. Block loads
double when the line turns 180 degrees. See example below. Select blocks
carefully.
Block Loading vs Angle of Deflection
Example shows single
footblock with a sheet
load of 5000 lb (2268kg)
8650 lb
(3923kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
10000 lb
(4535kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
3800 lb
(1723kg)
5000 lb
(2268kg)
5000 lb
(2268kg)
7000 lb
(3175kg)
5000 lb
(2268kg)
