ditions. Between 1972 and 1974 several experiments were held in 

 California and one in Michigan. These experiments included navigation 

 tests, instrument calibration, different data collection modes, evaluation 

 of experimental designs, and timing- of support operations (or the support 

 of other experiments) . 



The goal of all field experiments was to collect the most comprehensive 

 environmental data possible with the given capabilities. Thus, many sup- 

 port operations required collection of wind, temperature, and salinity 

 data, the areal reconnaissance of bottom roughness, and sediment prop- 

 erties. TODAS was used on several occasions to support radioactive 

 sediment tracing (RIST) . Most operations were conducted near coastal 

 engineering structures so that the results could provide insight to their 

 performance . 



TODAS is unique in that it is self-contained, i.e., requiring no 

 field installations or commercial power sources, and therefore can be used 

 at remote sites. It is applicable to both coastal and estuarine research. 



II. TOWED OCEANOGRAPHIC DATA ACQUISITION SYSTEM (TODAS) 



The separable and identifiable components of TODAS are: (a) The sea 

 sled; (b) the current meters; (c) the wave gage, onboard electronics, and 

 power supply; (d) the telemetry; (e) the onshore signal conversion; and 

 (f) the data conversion and recording units. Certain other components 

 attached by experimental design, such as the multispectral photographic 

 equipment used in imaging tracer dyes for charting surface currents, may 

 also be included. 



1. The Sea Sled . 



The functional parts of the sled are a 9. 14-meter- long mast, attached 

 crossmembers (spars) supporting current meters, a frame, and a pair of 

 skis on which the mast-spar assembly and two cylinders containing an 

 electronic package and the power supply ride. The total weight of the 

 sea-sled frame and the components of the data acquisition system mounted 

 on the sled is 347 kilograms (765 pounds), exclusive of additional weights 

 which can be added for more stability in a high-energy surf. Although the 

 sea sled has a low gravitational center, certain conditions can overturn 

 the platform, e.g., excessive wave forces, steep slopes, or a combination 

 of both. 



A calculation of the critical overturning moment and a description of 

 the upper (safe) limit of environmental conditions under which the sled 

 may be used in the field are given below. 



a. Wave-Force Analysis . In the operation of a structure at sea, two 

 commonly encountered hazards are structural damage (i.e., bending, break- 

 ing, and twisting of members) and overturning of an unanchored platform. 

 Both hazards are the result of excess wave forces. Thus, the design of 

 a structure requires a survey of wave and bottom conditions likely to be 



