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The Naval Surface Warfare Center, Carderock Division has developed a software tool, the Channel Analysis and Design Evaluation Tool (CADET), to aid in determining the operational depth of an entrance channel to commercial ports. CADET is a set of computer programs that use probabilistic risk analysis techniques to evaluate the accessibility of a series of channel depths for multiple vessel geometries and loading conditions. The operational depth is governed by many factors, including the geometry of the channel, local environmental conditions, and the hydrodynamic characteristics of the types of vessels that transit the channel. Shallow water vertical motions and the underway squat and trim are included. The wave environment is described using a climatology of local waves. The climatology includes the percent occurrence of combinations of significant wave height, modal period, and peak direction. These values are then converted into directional wave spectra and used to generate the ship motions for that wave condition. The accessibility of the channel for each project depth is then determined through calculating the risk of the ship impacting each project depth and the persistence of that wave condition at the channel. The CADET software distribution includes a MS Windows based program that provides a graphical user interface to the ship and project databases, the analysis software tools, and the results of project studies supporting design alternative analysis. This document provides a short summary of the theory upon which CADET is based, and instructions on how to use CADET.

The Joint Strike Force (JSF) Office at the Naval Air Systems Command (NAVAIR) tasked the Naval Surface Warfare Center, Carderock Division, to develop a ship motion database. The purpose of this database is to provide readily accessible ship motion data for air-capable ships to support design and development of JSF aircraft and to support shipboard operations. This report provides a description of the application and content of the database computer program as well as other supporting programs.

This report documents the mathematical model of a combined maneuvering, stationkeeping, and seakeeping simulation computer program for two different classes of mine hunting vessels. The model features a mix of physical based models for the propulsion systems and control surfaces and hydrodynamic coefficient based hull model. The approach follows the concept of the modular maneuvering model. A quasi-steady assumption is utilized for the seakeeping motion effects. This allows the calm water maneuvering motions to be calculated separately, and the six degrees of freedom linear responses in waves to be superimposed. The effects of wind, current, and second order mean drift forces are included.

A series of dynamic damage stability model tests have been performed on a CG-47 hull form filled with a double hull test section. These tests were carried out in support of the static and dynamic stability sub-tasks of the Advance Double Hull (ADH) Project. Various combinations of flooding conditions were investigated in regular beam seas, with and without wind. The model was subjected to regular waves ranging from 2.2 to 12.9 feet, single amplitude, with periods ranging from 5.3 to 19.9 seconds. These regular wave tests performed at the Carderock Division, Naval Surface Warfare Center (CDNSWC) in the Maneuvering and Seakeeping (MASK) basin. Calm water roll decay tests were also performed at the MASK while righting arm tests were performed at the adjacent drop tank facility. These test were performed in order to calibrate the static stability and roll damping characteristics of the physical model to those of associated computational models. (KAR) P. 3

The U.S. Navy is currently investigating the concept of an advanced, unidirectionally framed, double hull surface combatant ship design. This report documents the results of an investigation into the damage stability issues involved. Comparisons have made between a conventional monohull surface combatant and the vessel modified with double hull compartments. Double hull configurations internal and external to the original hull shell using three foot and six foot spacings were considered. Several watertight compartmentation geometries within the double hull spaces were also investigated. The Ship Hull Characteristics Program (SHCP), version 4.11 was used for intact and damaged stability calculations. Damage conditions evaluated were specified by Navy Design Data Sheet (DDS) 079-1 dated 1 August 1975, for the stability and buoyancy requirements for U.S. naval surface ships. The stability criteria as specified in DDS 079-1 were applied and evaluated for the double hull CG 47 computer models. Additional damage conditions and stability criteria evaluated were taken from the U.S. Coast Guard standards adopted for double hull oil tankers. It is concluded that the double hull concept does have an adverse effect on damage stability and that the existing Navy stability criteria is adequate for double hull combatants. (KAR) P. 3

Results of a study on seakeeping and resistance optimized frigate hull forms are presented. The seakeeping optimization is based on the work of Walden and Grundmann. Resistance calculations are based on the method of Holtrop. The effects of cost function weighting factors are discussed. The combination of a procedure for generating a hull form from a set of coefficients, a simple seakeeping measure of merit a resistance estimation procedure, and an optimization program has resulted in a powerful tool for use in early design.