Lift Line Dynamics: A Technique Tailored for the User

A technique is proposed as an aid to the marine salvage master at sea and the ocean engineer. The aid may be used to find line size, factors of safety, maximum operating conditions, salvage object parameters and other useful information relating to the lifting or lowering of heavy objects at sea. A computer program based on Arthur D. Little, Inc. equations for maximum dynamic line force is used to generate a number of parametric curves for a specific ship lift point and line type which are then collapsed into one simple equation--the key formula--for dynamic factor of safety. This is combined with the easily obtained static factor of safety, and the results displayed on a set of homographs and charts. The paper explains the need for such a scheme, what the basic equations mean, their limitations, and how the charts and homographs are used.