Oscillation. Oscillation of the load is a measure of the effect of 

 surface vessel motions on the load. For instance, it is possible for the heave 

 of a ship to be magnified at the lower end of a pipe string. Obviously, this 

 action could result in serious damage to the load as it approaches the ocean 

 floor. It is felt that the potential for oscillation and the potential for 

 combating it should be accounted for in this study. A weighting factor of 

 two has been assigned to this figure of merit. 



Load Transfer at the Surface. This factor is a measure of the ability 

 of a system to receive loads while remaining on station. This may be one of 

 the most important factors in choosing a system if the predictions of modular 

 construction for underwater installations prove to be accurate. While the 

 latter predictions are yet to be fulfilled, most thinking in the industry is 

 leaning in this direction. Consequently, a heavy-lift system may be useful 

 only if it can receive and transfer modules from other surface vessels while 

 on station. A weighting factor of three reflects the importance associated 

 with this operational characteristic. 



Sensitivity to Sea State. The sensitivity of a system to the sea state 

 is given a weighting factor of two. The higher ranking systems in this 

 category can operate in more severe sea states. Those systems highly 

 susceptible to the state of the sea (or severely constrained by it) are given 

 lower rankings. 



Sensitivity to Water Density. The sensitivity of a system to water 

 density is concerned with subsurface operations. Systems for which buoyancy 

 is necessary are particularly susceptible to changes in water density. The 

 difficulty of sensing and accounting for these changes is measured in this 

 figure of merit. The weight assigned is two. 



Sensitivity to Water Currents. It was found during the course of the 

 study that some systems could very easily be affected by even average 

 currents (particularly with respect to positioning). The difficulty and/or 

 possibility of counteracting these effects are indicated by the value assigned 

 this factor. A weight of two is considered appropriate. 



Placement Potential. The positioning of a load is considered to be 

 of some importance. The desirability and feasibility of installing active 

 positioning systems, such as underwater winches, or simply moving the 

 surface vessel for positioning the load are given consideration in this figure 

 of merit. The surface-supported systems were ranked about equally. Some 



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