T&R Bulletins & Reports

The design of specific equipment installed in ships is usually accomplished by fires other than the Shipbuilder. As a consequence of this situation, the Shipbuilder does not have direct control over a significant portion of the weight of the ship being built. For shipbuilders to have direct control of equipment weights is neither necessary nor desirable. Shipbuilders cannot be experts in the design of all equipment. Control of equipment weight my be maintained in the same manner that any other equipment characteristic is controlled; through specific weight requirements in the technical portion of the Request for Quotation and the Subsequent Purchase Order. The degree of weight control to be specified will be influenced by the cost of that weight control, requirements of the shipbuilding contract, and the sensitivity of the ship’s performance to weight and its distribution.

The general arrangement design is documented by the general arrangement drawings. The general arrangement drawings define design requirements which are described pictorially rather than in words. The drawings should be as self-contained as possible. They should not repeat the requirements in the ship specifications but should amplify them. Extraneous detail not identified in the ship specifications, should not be shown as the risk of it changing or conflicting with the specifications is too great.

The general arrangement design is documented by the general arrangement drawings. The general arrangement drawings define design requirements which are described pictorially rather than in words. The drawings should be as self-contained as possible. They should not repeat the requirements in the ship specifications but should amplify them. Extraneous detail not identified in the ship specifications, should not be shown as the risk of it changing or conflicting with the specifications is too great.

The design of a ship’s General Arrangements is subject to a host of criteria and constraints stemming from physical, operational, and mandated restrictions. These impositions on the ship designs pan a wide range of considerations reflecting owner or mission needs, legal requirements, operator considerations, safety, system needs, convention, and support facilities. Since the General Arrangements represents the core of ship design, the criteria and constraints must be satisfied as a necessary condition for developing a viable craft.

The selection of stability criteria has an enormous impact on a 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 bulletin documents those features of SWATH ships judged to be of importance of prospective SWATH ship owners and designers. The basis for this document is the information available for the SWATH ships produced as well as the supporting technology. The information provided forms a basis for assessing the capabilities and limitations of the SWATH concept as well as providing an overview of SWATH technology. The overall design of SWATH ships as well as major topics such as structures, loads, machinery, and hydrodynamic performance are discussed in general terms to provide a general understanding of them. A more detailed treatment of these subjects is available through the more specialized technical literature indicated by the references.

The Software User's Manual for the Propeller Selection and Optimization program (PSOP) is intended to present the elements necessary to install and execute the computer program. It contains a description of the theory employed in the program as well. The manual provides a complete listing of the source code of the program.

Compartment and Access (C&A) drawings define and document a ship’s configuration for the development of a detailed design. The C&A Drawings are used to define the boundaries of compartments for the development of access openings, passageways, piping and ventilation systems, damage control closures, structural interferences, and hull outfit layouts. Accesses shown on the drawings are defined for both personnel and equipment removal as identified on the contract general arrangement drawings and the specifications. The details on the C&A drawings should be specifically and clearly defined to provide detailed design personnel with information to develop distributive systems.

The purpose of this Bulletin is to document naval architectural practices and conventions used in the estimation and determination of the weight, centers of gravity and weight moments of inertia for surface ships, and to reference sources of weight estimating data for ships and their components for use at various stages of design.

Conventions and practices for offshore drill rigs, high-speed craft, and submarines are mentioned in some instances to demonstrate alternative methodologies but are documented only by references. Military practices and conventions are summarized and referenced but not fully documented.

The purpose of this Bulletin is to document naval architectural practices and conventions used in the estimation and determination of the weight, centers of gravity and weight moments of inertia for surface ships, and to reference sources of weight estimating data for ships and their components for use at various stages of design. Conventions and practices for offshore drill rigs, high-speed craft, and submarines are mentioned in some instances to demonstrate alternative methodologies but are documented only by references. Military practices and conventions are summarized and referenced but not fully documented. Throughout this document, the term weight is used to represent all the mass properties of a ship or object. These properties include the weight, center of gravity, weight moments, and weight moment of inertia.

Technical studies provide insight into leaders that help them make decisions. These decisions can be of small magnitude or could impact the expenditure of billions of dollars and the lives of many individuals. Following repeatable, documented engineering processes to produce reliable and timely technical studies can significantly enhance the quality of these decisions.

This guide was written for engineers and naval architects in planning and executing technical studies.