ABS: Structural Direct Analysis for High-Speed Craft

The American Bureau of Shipping has published the Guidance Notes on Structural Direct Analysis for High-Speed Craft.

This document was issued on 1 April 2023 and became effective on the same date.

These Guidance Notes are an extensive revision of and supersede the ABS Guidance Notes on ‘Dynamic Load Approach’ and Direct Analysis for High-Speed Craft (February 2003). This revision is effective 1 April 2011.

These Guidance Notes provide information about the analysis procedure for Structural Direct Analysis, which is available to assess the strength of high-speed craft and light warships, patrol, and high-speed naval vessels.

In addition, they provide guidance to be followed when submitting required direct analyses or such analyses submitted in place of standard calculations.

Section 1-1-3 and Section 1-2-2 of the ABS Rules for Conditions of Classification – Light and High-Speed Craft (Part 1) contain descriptions of the various basic and optional classification notations available for high-speed craft.

The requirements for Direct Analyses are specified in Section 3-1-3 of the ABS Rules for Building and Classing High-Speed Craft (HSC Rules).

Section 1-1-3 and Section 1-3-2 of the ABS Rules for Conditions of Classification – Light and High-Speed Craft (Part 1) contain descriptions of the various basic and optional classification notations available for light warships, patrol, and high-speed naval vessels.

The requirements for Direct Analyses are specified in Section 3-1-3 of the ABS Rules for Building and Classing Light Warships, Patrol, and High-Speed Naval Vessels (LHSNV Rules).

The July 2022 version expands the guidance on using model test data to obtain extreme global responses given in Subsection 4/7.

The April 2023 version adds additional descriptions of whipping loads as well as some practical methods to account for such loads, with a focus on twin-hull vessels.

Current Regulations on High-Speed Craft

The International Code of Safety for High-Speed Craft (IMO, 2000) is the only IMO document addressing high-speed craft.

It applies to all types of craft operating internationally, but Chapter 3 of the IMO document deals with structures only in a basic manner.

The requirements for direct analyses to be performed, based on craft length, speed, and other special features, however, are stipulated in the following documents:

i) ABS Rules for Building and Classing High-Speed Craft (HSC Rules)
ii) ABS Rules for Building and Classing Light Warships, Patrol, and High-Speed Naval Vessels (LHSNV Rules)

Naval Requirements

ABS, with the assistance of the U.S. Navy, has developed the LHSNV Rules for high-speed craft for a range of operations.

Naval requirements specify that high-speed craft are to be designed to technical standards that will provide the safety and operational effectiveness required for the intended mission.

Currently, most high-speed crafts are designed, built, or classed for restricted service.

Use of any high-speed craft with a mission that requires unrestricted open-ocean operations should be evaluated for safety using the requirements of the LHSNV Rules, especially if initially designed or classed for restricted service.

This safety evaluation will invariably require a structural assessment that involves direct analysis designed to identify the operational limits.

If you need more information, please visit the ABS Rules and Guides page, where the document is available FOR FREE.