Safe securing of Trailers and deck cargo

Securing of trailers and deck cargo on board ro-ro vessels is an important aspect of good seamanship. Failure of lashings and subsequent shifting of cargo elements provide a serious safety hazard. The paper investigates the loading of lashing gear on board Ro-Ro ships. First the nature of the lashing loads, with important effects of the lashing geometry is explored. Based on work by Andersson et.al [1982] a linear model, accounting for the mutuat phasing of the external loads, is derived. Secondly the external loads, with important effects of the position on the ship and the ship heading with respect to the waves, are discussed. Based on a typical wave climate the risk of lashing failure is quantified. For an interesting case the applicability of Standard lashing arrangements on board ships with increased stability characteristics is discussed. The applied calculation method as such is not an alternative for the existing rules and recommendations, like IMO (resolution A.581(14), 1985) or the recommendations at the UK Nautical Institute [Knott, 1985]. Using it in a comparative way it may be particularly useful in the evaluation of special transports or a comparison of alternative ships, ship arrangements or the climates prevailing on various ship routes.