TOWING CHARACTERISTICS OF AN UNDERWATER 

 RADIATION DETECTOR VEHICLE 



INTRODUCTION 



Appendix B is a report of an investigation to evaluate the required 

 hydrodynamic performance of the detector vehicle. The investigation was 

 made for the Coastal Engineering Research Center (CERC) by the Naval Ship 

 Research and Development Center (NSRDC). The program included towing the 

 vehicle at speeds up to 6 knots in three modes as follows: (a) in a sus- 

 pended attitude, (b) in a survey attitude (rolling on basin floor)., and 

 (c) using various cable lengths with additional weight on the vehicle. 

 The cable tension, cable angle, and tracking attitude were observed for 

 each towing mode. 



This report contains a description of the detector vehicle and test 

 procedures, presents the results of the towing tests and observations of 

 the vehicle towing attitude, gives predictions of the cable configurations 

 assumed by the towcable, and makes recommendations for modifications. 



DESCRIPTION OF VEHICLE 



The detector vehicle furnished by CERC to NSRDC for the tests is 

 shown in Figure B-l. The vehicle, designed to roll along the bottom in 

 its survey attitude, consists of a cylindrical housing made of expanded 

 metal reinforced on its rolling surface with stainless steel rods . The 

 detection mechanism and electronics assembly, which is pendulous, is 

 attached to a shaft through the housing that provides protection for the 

 assembly. A tow bail is attached at each end of the shaft and provides 

 for a single-point towcable attachment. The electrical cables for the 

 detection equipment exit from one end of the shaft, are attached along 

 the tow bail to the towcable attachment, and then are married to a 1/k- 

 inch-diameter wire rope towcable. Physical characteristics of the 

 detector are listed in Table B-I. 



TABLE B-I 



Physical Characteristics of Detector Vehicle and Towcable 



Overall width, inches 50 



Overall diameter, inches 30 



Housing width, inches h2 



Height, inches 30 



Distance from center shaft to towpoint , inches 32 



Model weight in air, pounds 505 



Model weight in fresh water, pounds UlO 



Towcable weight per foot in air, pounds 0.6 



Towcable weight per foot in fresh water, pounds .h 



B-2 



