There are multiple factors to consider when designing an External lashing system. Always seeing the full picture during the design phase assures a safe and efficient lashing system.

No matter size and age of a container vessel; containers on deck are secured with almost the same equipment on all of the vessels. A lashing bar is connected to a container corner casting, the lashing bar is connected to a turnbuckle and the turnbuckle is connected to an eye plate that is welded to the hull structure (deck, hatch cover or lashing bridge). It has been default for the majority of the world's container vessels to use an Internal lashing system where the containers are secured with the lashing bar to the corner casting on the compression side of the container stack.

An External lashing system secures the containers with the lashing bar to the corner casting to the lifting side of the container stack. Lashing this way reduces both the lifting and compression forces that the container stack is exposed to during rolling. This allows for more flexibility in stack weight distribution - each stack can carry heavier and potentially more containers than a stack secured with Internal lashing.

An External lashing system has to be tailor made for each vessel series due to various factors, e.g. lashing bridge heights, transversal gaps between containers and longitudinal distances from container end to lashing bridge. Safety is always top priority during the design stage. The lashing system is designed to use as light weight equipment as possible to reduce injuries caused when handling the lashing equipment. The lashing system is designed so that one type of lashing bar is used in all positions on each lashing bridge to assure that there is no reduction of safety due to the use of wrong equipment when securing the cargo. Stowage systems for lashing bars and turnbuckles are designed for safe, easy and efficient handling.

The lashing system undergoes a full scale mock-up test to assure that the lashing equipment is correctly designed with respect to equipment lengths and types, handling and durability.