The effect of the guideline anchor on the guide frame rotation 

 along the guideline length can be visualized as shown in Figure 1 1 . 

 The orientation of the guide frame depends on the relative position of 

 the lift line and the guideline. The position of the payload is mainly 

 controlled by the prevailing current speed and direction. The position 

 of the payload as projected on a horizontal plane, together with the 

 guideline, are shown in the plan view. Note that the guide frame 

 rotates a substantial amount from the surface to the seafloor. The 

 effect of the guideline tension, the suspension depth, and current con- 

 ditions could not be identified due to the scatter of the data. The 

 measured data indicate little dynamic activity of the guide frame. 

 About 90% of the rotational oscillations have a peak-to-peak value of 

 20 degrees. The maximum recorded variation is 40 degrees. The payload/ 

 guide-frame system is, therefore, considered stable. 



It is not likely that surface excitations could trigger a large 

 amplitude oscillation that would eventually lead to entanglement. The 

 main conclusion of the shallow-water, single guideline tests is that the 

 rotational motion of the guide frame depends solely on the static forces 

 acting on the whole cable system rather than the dynamic excitations 

 applied from the top. In other words, the decoupling of the surface 

 effect from the guideline system is quite effective. 



For a general guideline design it is not required to know the 

 orientation of the guide frame at various depths: the only concern is 

 the entanglement. If a complete solution of the guideline system is 

 required, the problem can become quite difficult. Methods are available 

 for the solution of complex three-dimensional cable structures, but the 

 task is by no means small (Reference 7) . Appendix A presents an approxi- 

 mate solution for a quick analysis of the guide frame rotations. This 

 method is presented here for those who wish to make a qualitative 

 analysis of the payload orientation at various depths along a single 

 guideline. Based on the relative guideline displacement concept, the 

 direction of guide frame rotation can often be predicted without an3/ 

 calculation. 



The results of the deep-depth tests are presented in Figure 9. All 

 three test runs are stable, but the rotations are usually sudden. 

 Apparently, the rotations are results of readjustment of the equilibrium 

 position. Dynamic oscillation is not observed. The double guideline 

 tests seem to have more stable motion throughout the tests--near the 

 surface, in particular. If bottom mating and orientation control are 

 not required, a single guideline is considered effective for entangle- 

 ment-free operations. 



The entanglement observed in test run Dl was probably caused by an 

 unexpected slack developed at the lower end of the guideline. The upper 

 end of the guideline was tensioned by an air-operated winch, which, how- 

 ever, must have failed to develop enough tension to support the entire 

 weight of the guideline. This winch could not maintain constant tension 

 when working at the lower end of its rated load range. A smaller winch 

 would provide better tensioning, but the spool would be too small for 



