Friction included or excluded in calculations?

Friction included or excluded in calculations?

Oct 02 2014


Friction is a magic word in transport engineering.
For some companies it means saving money on lashing & securing. For another companies it means to create additional safety for the cargo. When is friction used? How is it used?

We all know what the coefficient of friction will be when using steel on timber, or steel on steel etc. Some rubber mats manufacturers state they have mats which could create a coefficient of 0,8g. Amazing…No more lashing and securing for shear forces!

For some reason many people think that when we use DNV for acceleration calculations, it’s always 0g friction. When you ask them why, they state that it is always like this. Using zero friction for a load-out is done when steel-steel was used in UAE in some load-outs long ago, because there was almost no timber available so zero friction was used. That’s the reason people thought it should always be like this for DNV.

As we know that class approved load-outs often dictate the amount of friction allowed to be used, it still results many times in extensive over-lashing and securing. In the end someone has to pay for this, which minimizes the profit on a load-out. If margins disappear, there will be no money earned to educate people what it is all about. No education means not knowing, means more and more regulations and rules laid up by other elements in this maritime chain of events.

Do you use friction because IMO states it is allowed and you are rightful to do so, or are you bending for the new ‘rulers’, who dictate and expected to be obeyed?

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2 Comments on "Friction included or excluded in calculations?"

November 26, 2014

It is important to understand that IMO committees have various members, including ship-owning representatives. Therefore these agreed ‘rules’ are a balance between interests, where notably the shipowners are most interested in less lashing (cheaper). Comment box is too small for a complete answer..

Thomas Janssen
October 7, 2014

“Friction is for free and given by the Lord. Hence it should be taken into consideration! If you want to play it save then you still can choose a higher GM. In my world, overlashing of cargo is as worse than underlashing. Lashing on the point taking the nature of the cargo into consideration is the