Calculation example

Steel plates in eight layers are loaded on a roll trailer. Each layer has a weight of 10 ton meaning that the total weight is 80 ton. Wooden dunnage is used between each layer.

Chain lashings with MSL 7.5 ton are used for the securing arrangement consisting of loop lashings for securing of the steel plates in transverse direction and spring lashings in longitudinal direction.

TRANSVERSE DIRECTION:

According to the rule-of-thumb, four of the layers are loop-lashed together in the bottom and four in the top. The number of loop lashings is to be determined based on the weight of the

layers of cargo they encircle as well as the weight of any layers stowed on top of it. This means the following:

1. Bottom four layers:
   • Four pairs of loop lashings - 4 x 22.5 ton = 90 ton > 80 ton (Secured for 100% of weight)
2. Top four layers:
   • Two pairs of loop lashings - 2 x 22.5 ton = 45 ton > 40 ton (Secured for 50% of weight)

In total six pairs of loop lashings are used to secure the steel plates in transverse direction.

LONGITUDINAL DIRECTION:

The number of spring lashings used for securing the steel plates in longitudinal direction is calculated as follows:

One pair of spring lashings - 1 x 102 ton = 102 ton > 80 ton

In total two pairs of spring lashings, one per end, are used to secure the steel plates.