Calculations: why tie down placement is important
Assuming that there is 150 lbs. tension in each tie-down Strap and assuming the geometry as shown in Figures 7 and 8.
Front (Figure 8a)
The tie-down tension can be broken down into its horizontal and vertical components:
The horizontal force can be further broken down into its forward (fore) and lateral components:
Rear (Figure 8b)
The tie-down tension can be broken down into its horizontal and vertical components:
The horizontal force can be further broken down into its rearward (aft) and lateral components.
Since the geometry and tension is equal for both front straps the total fore force is equal to 2 times the fore force or 136 lbs.
Since the geometry and tension is equal for both rear straps the total aft force is equal to 2 times the aft force or 18 lbs.
The fore and aft imbalance is 118 lbs. (136 lbs. - 18 lbs.)