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Block Size and load information

The size of block that you choose to use on your boat is a vital step in the process of buying your new Garhauer block. The working load of your block depends on the angle of the sheet on the block and the load on the line. To help you decide what series of block you need in each particular case we have provided the table below to help you calculate what you need.
Block Load Diagram
Angle of Sheet (degrees) Percentage of Line load on the Block   Angle of Sheet (degrees)
Percentage of Line load on the Block
         
10 17    105 159
20 35   120 173
30 52   135 184
45 76   160 197
60 100   170 199
75 122   180 200
90 141      
Angle of Sheet (degrees) Percentage of Line load on the Block
     
10 17 
20 35
30 52
45 76
60 100
75 122
90 141
   
Angle of Sheet (degrees)
Percentage of Line load on the Block
   
105 159
120 173
135 184
160 197
170 199
180 200
   

This means that when the angle of the line on the block is at 60 degrees, the maximum load on the block has been reached so the line load can be at most the full Safe Working Load. For example, if the block has a SWL of 900kg, if the line through the block is to be at 60 degrees, then the line load can be at most 900kg. Similarly if the angle of the sheet on the block is 180 degrees, then the max load on the line would be half the SWL. In the case of our 900kg SWL block, the max load on the line would be 450kg.
Once you know the max load that you need your block to manage, please use the table below to help identify the range of block to investigate.  Please note there are high load blocks available in the single block range to increase the SWL.  These high load blocks are for the 40-70 series single blocks.
Series 15 20 25 27 30 40 50 60 70
Max Line Size
5/16"
8mm
5/16"
8mm
3/8"
10mm
3/8"
10mm
1/2"
12mm
1/2"
12mm
5/8"
16mm
5/8"
16mm
3/4"
19mm
Sheave Diameter
1"
25mm
1-3/4"
44mm
2"
50mm
2-1/4"
57mm
2-1/2"
63mm
2-1/2"
63mm
3"
76mm
3-1/4"
82mm
4-1/4"
108mm
Safe Working Load
400lb
182kg
600lb
272kg
1150lb
520kg
2000lb
907kg
2400lb
1088kg
2800lb
1270kg
3000lb
1360kg
3500lb
1590kg
5000lb
2267kg
Series 15 20 25 27 30
Max Line Size
5/16"
8mm
5/16"
8mm
3/8"
10mm
3/8"
10mm
1/2"
12mm
Sheave Diameter
1"
25mm
1-3/4"
44mm
2"
50mm
2-1/4"
57mm
2-1/2"
63mm
Safe Working Load
400lb
182kg
600lb
272kg
1150lb
520kg
2000lb
907kg
2400lb
1088kg
Series 40 50 60 70
Max Line Size
1/2"
12mm
5/8"
16mm
5/8"
16mm
3/4"
19mm
Sheave Diameter
2-1/2"
63mm
3"
76mm
3-1/4"
82mm
4-1/4"
108mm
Safe Working Load
2800lb
1270kg
3000lb
1360kg
3500lb
1590kg
5000lb
2267kg
Series 15 20
Max Line Size
5/16"
8mm
5/16"
8mm
Sheave Diameter
1"
25mm
1-3/4"
44mm
Safe Working Load
400lb
182kg
600lb
272kg
Series 25 27
Max Line Size
3/8"
10mm
3/8"
10mm
Sheave Diameter
2"
50mm
2-1/4"
57mm
Safe Working Load
1150lb
520kg
2000lb
907kg
Series 30 40
Max Line Size
1/2"
12mm
1/2"
12mm
Sheave Diameter
2-1/2"
63mm
2-1/2"
63mm
Safe Working Load
2400lb
1088kg
2800lb
1270kg
Series 50 60
Max Line Size
5/8"
16mm
5/8"
16mm
Sheave Diameter
3"
76mm
3-1/4"
82mm
Safe Working Load
3000lb
1360kg
3500lb
1590kg
Series 70
Max Line Size
3/4"
19mm
Sheave Diameter
4-1/4"
108mm
Safe Working Load
5000lb
2267kg
If you are unsure of your line loads or need help to figure out what block suits you best, please feel free to contact us using the online form or call (Ph: +64 9 4026231 Mob +64 22 3800871.