The Limitations of Tie Down Lashing

The simplest method of load securing is tie-down lashing. This involves placing at least two lashing straps over a cargo unit, such as a box or crate, which are then tightened to the correct tension using a suitable ratchet. This does not secure the object. Tightening increases the friction between the object and the cargo floor, which reduces the likelihood of the object moving. The tighter the straps, the greater the friction. But if there is a force greater than the friction, the object will move. 

A simple calculation can be used to determine what kind of lashing straps should be used and with what force. This is the so-called pretension force (STF).

Limitations of tie down lashing

Tie down lashing has two very important limitations:

1. Tie down lashing is not suitable for extremely heavy loads, because a disproportionately large number of lashings must be used. Using friction materials  is possible in some cases, but the capacity of the straps must be calculated accurately in advance and they must be applied very precisely.

Friction between objects

2. Objects standing or lying on top of each other should never be secured using tie down lashing. This is because the calculation when tie down lashing is based on the friction between the bottom object and the loading floor. When stacking, the friction between the objects themselves must also be taken into account. If, for example, steel beams are involved, they have very little friction in relation to each other and the risk of sliding during abrupt braking, for example, is very high. This therefore requires separate calculations, where a solution can be found by applying friction materials between the loaded objects. 

Importantly, the lashing angle, the angle between the lashing device and the loading floor, should be as big as possible.