It is obvious that the motions of the platform decrease significantly 

 as the draft increases. In an oblique heading, the motions are generally less 

 than a head or beam heading for the same sea state and draft. Based on 

 intuition, it would seem likely that a platform or ship would heave less headed 

 into the sea than having its full length exposed in a beam sea. The smaller 

 motions of the platform in oblique seas are not as obvious, but important, 

 since this does give more leeway in how the platform can be oriented. On 

 the other hand, a ship will require a fairly accurate heading, especially in the 

 more severe seas. This is important only if the direction of the predominant 

 sea can change rapidly. 



CONNECTING THE PIPE TO THE LOAD 



The problem of disconnecting the pipe from the load after it has been 

 placed can be solved by at least three techniques: 



1 . Use of a robot 



2. A hydraulic actuated mechanism 



3. A mechanical device 



Examples of two of these approaches are illustrated in Figure B-1 7. 



There are some important factors to consider in the design of the 

 connector. Of primary concern are the difficulties of remote operation of 

 mechanisms at a great distance. This is a problem when the load is to be 

 disconnected from the pipe, but it is a special problem when the pipe must 

 be reconnected to the load. The latter problem of location and reconnection 

 can be solved in a number of ways; some of the more promising of these are: 



1. Use of a manned submersible. 



2. Use of underwater television, such as a CURV-Wke vehicle. 



3. A permanent vertical cable, from the load to a submerged buoy, 

 which could serve as a guideline for the connector. 



It does not appear feasible to have a heavy-lift system which would 

 have the capability of lifting all types of loads; it is not possible to have 

 simple and dependable connectors that will accommodate all types of loads. 

 Thus, the load will have to be designed with the lift system in mind; for 

 example, for the pipe string system only one lifting point is allowable. 



136 



