T&R Bulletins & Reports

This document provides a guide to be used during the pre-contract stage of ship design to achieve a "lean" design with reduced work scope. It provides a collection of documented best-practices and design guidelines based on world-class product-oriented ship design processes stressing the need to make all key ship arrangements, system design, and construction decisions early in Basic or Pre-contract Design.

The document is intended as a reference for ship design managers and Integrated Product Teams (IPT) charted with the development of high-quality and low-cost contract designs. Additionally, the guide provides state-of-the-art training material for students of Naval Architecture and Marine Engineering.

Set-based design (SBD) is a method for performing design discovery by way of elimination. SBD is characterized by:

1. communicating broad sets of design values, 2. developing sets of design solutions, 3. evaluating sets of design solutions by multiple domains of expertise, 4. delaying design decisions to eliminate regions of the design space until adequate information is known, and 5. documenting the rationale for eliminating a region of the design space. SBD concentrates on eliminating infeasible and highly dominated regions of the design space. An infeasible region is a region where there is high confidence that a solution does not exist. A highly dominated region is a region where another feasible region is evaluated as being better in every metric of interest. Regions of the design space can be confidently eliminated based on partial information. In SBD, the ultimate solution is obtained incrementally as new information is incorporated.

To be precise, many decisions are made regarding what the solution is not; this occurs as supporting information becomes available. The remaining analysis may focus on reduced design space. In this manner, designs can often be accomplished faster and with greater robustness as compared to traditional methods.

This guide is developed to provide weight classification guidance and process improvements to augment the U.S Navy’s 1985 Edition of the Expanded Ship Work Breakdown Structure (ESWBS). In recent years naval architects and shipbuilders have introduced new technologies into ship designs and construction practices. The current ESWBS classification does not provide adequate guidance on how to use the weight classification for new technologies, systems, and practices. As a result, SAWE and SNAME jointly set up a workshop(s) to identify and provide guidance to address the proper classification of these newer systems for the appropriate assignments in the weight estimates for future ships as well as to provide a means to cross reference previous historical weight data. Also, the workshop(s) reviewed the current ESWBS and recommended modifications to help ensure that the potential of duplications, missed classification of weight data, inconsistencies within ESWBS, and provide greater clarification in the future as well as assist in cross referencing of historical weight data. A technical paper and presentation were made at SAWE’s Annual International Conference in 2015 [1], which documented the initial findings of the workshop. This guide is a result of over a ten-year effort and is intended to be used as guidance to augment the classification of weight reporting using the 1985 Edition of ESWBS [2].

For the safe operation of ships at sea, stability determining the operability of a ship and its survivability after damage. Because the mission requirements for commercial and naval ships are so enormously different, their requirements for operability and survivability are also vastly different.

The selection of stability criteria has an enormous impact on the ship's arrangement in terms of subdivision, access, and functional location of compartments. In addition to access and compartmentation impacts, ship support systems such as piping and heating, ventilation, and air conditioning (HVAC) are also affected. The degree of impact on a ship's arrangement can be directly related to cost and survivability depending on the stability criteria selected. The deciding factors for determining the stability criteria to be used should consider the operation of the ship and -the degree of safety that the cost constraints of a ship design program can afford, without severely impacting the configuration of the ship to meet mission requirements.

The objective of this paper is to identify the various stability requirements and to assess the impacts on the general arrangement and ship systems. This assessment is intended to provide a quantitative means of evaluation for determining the appropriate stability criteria which best suits a particular ship's mission.

This report examines the hull form options available for high-performance ferries. It is intended as a tool for the preliminary selection of the most appropriate hull form for a particular application. The terms used to describe advanced hull forms are defined and discussed in Appendix A.