As vessels are getting bigger, structural strength assessments during the design stage are important ensuring the safety and integrity of hull structures even in the harshest conditions of the ocean.

Direct strength calculations in structural strength assessments of hulls are one of the class requirements included in both ClassNK’s “Rules and Guidance for the Survey and Construction of Steel Ships” and the International Association of Classification Societies’ “Common Structural Rules” (IACS CSR).

Simple formulae, which calculate loads according to principle ship particulars and loading conditions, are carrying out structural strength assessments. However, these formulae were developed to cover load conditions estimated from actual ships, and have not yet been evaluated for increased sizes and configurations of vessels not yet constructed. As a result in some cases, structural strength assessment that takes the loads of each individual vessel characteristics into account is vital.

Structural strength assessment methods based on “load and structural consistent analysis” consider waves at sea when estimating loads, and are able to replicate actual ship conditions. Thus, shipyards and design companies are using these assessment methods.

These guidelines will be updated to reflect the latest findings from research and development initiatives. The class notation “PS-DA-DLA” and/or “PS-FA-DLA” is respectively affixed to the classification characters of a ship when strength assessments have been carried out for all cargo areas in accordance with the guidelines.

To see the guidelines, click here