The change in specific volume for seawater as a result of the changes due to 

 temperature, salinity, and pressure was determined from 



Av = AV,3 + AVp 



where AV^j = a^s ^^ 



AVp =AP/Kp 



a^5 = coefficient of thermal expansion 

 At = temperature change 

 Av = change in specific volume 

 Kq = effective bulk modulus 



in the second method the change in density due to temperature and salinity 

 was determined from changes in specific gravity, or 



Adt3 = 64.176 (AP) 



64.42 AVp 



and Ad„ = :: 



The above analysis demonstrates that a submerged object will gain 

 buoyancy during descent. This behavior results in a decreasing velocity as the 

 plant descends to the bottom and allows it to return to the surface by 

 jettisoning diving weight. The change in buoyancy establishes the amount of 

 diving weight required and presupposes that the plant without this diving 

 weight is neutrally buoyant near the surface. 



Hydrodynamic Stability. A careful study of the plant's hydrodynamic 

 characteristics was required to achieve both hydrostatic and dynamic stability 

 and to properly configure an in-situ plant for successful deployment. A 

 detailed analysis of the equations of motion of vertically rising or falling 

 bodies in a fluid established velocity and displacement history curves and 

 determined the drag coefficient and amount of ballasting required for neutral 

 buoyancy at the bottom.* 



For the plant to be hydrostatically stable, the center of gravity must 

 be below the center of buoyancy to assure that the plant will not capsize. The 

 center of gravity of the plant should also be ahead of the hydrodynamic 

 neutral point. Consequently, it may be necessary to add stabilizing devices 

 (fins) at the upper end of the plant in descent and at the lower end in ascent. 



Contract Report CR-68.004, 02.. cit 



27 



