ABSTRACT 



The David Taylor Model Basin was requested to make a quantitative study 

 of the motion characteristics of the NRL Alternate 1 Stable Platform Concept 

 (FORDS). Tests were conducted in the Seakeeping Facility on a 1/40-scale 

 model in regular and Irregular waves. In general, the motions at the 

 light draft were comparable in magnitude to those of a cargo- type ship of 

 the same displacement. However, at the deep or operating draft, the 

 motion of the platform was reduced considerably. 



INTRODUCTION 



The Naval Research Laboratory is conducting feasibility studies of 

 stable platforms to determine requirements for testing and evaluating large, 

 low- frequency 5 acoustic transducers in ocean surveillance applications. 

 An important part of this work is to make accurate measurements of the 

 motions of scaled models in order to reach decisive conclusions on a suit- 

 able stable platform configuration. As a part of this study, the Taylor 



Model Basin was requested to conduct scaled model tests of a proposed stable 



1 

 platform design. 



In January 1963, a 1/120- scale model of NRL Alternate 1 Stable Platform 



Concept (FORDS) was tested in the TMB 140- ft basin. Because o>f the small 



model and the instrumentation limitations, only qualitative results were 



obtained. It was then decided to test a larger model (1/40-scale) in the 



Maneuvering and Seakeeping Facility, and these tests were conducted in 



November 1963, 



1 

 References are listed on page 7 



