CONCLUSIONS 



The positioning of a surface vessel should present no problems at any 

 location off the continental United States. Accuracy of ±30 feet appears 

 acceptable for work under water and, in addition, is within the state-of-the- 

 art. 



For holding position, a dynamic positioning system is the most 

 desirable. Positions can be held to within 2% of the operating depth with 

 units currently in use. 



Dynamic positioning systems are superior to conventional moorings 

 from both operational and economic standpoints (at least for heavy-lift 

 operations). Vessels of 5,000 to 10,000 tons displacement have been moored 

 in deep water, but the cost has been excessive; for a mooring in 600 feet of 

 water, the total cost may approach $500,000 for anchors, chains, winches, 

 and auxiliary equipment (Reference 26, p. 5.5). Unless a mooring system is 

 to be used for a long time, it is safe to state that a dynamic positioning system 

 is superior for operations in water depths in excess of 300 feet. 



102 



