where 0:2 = bottom angle of inclination 

 D2 = total subsui'face drag, lbs 

 T= assumed tension, lbs 



Next the arc radius was computed : 



(V) 



D2-D1 



E=arc radius, ft 



Z = water depth, ft 



T= assumed tension, lbs 

 ©2 = total subsurface drag, lbs 

 Di = surface buoy drag, lbs 



After solving for E, the arc length was 

 calculated : 



S = E (a.-a^) (8) 



where S = arc length, ft 

 11 = arc radius, ft 

 Q'2 = bottom angle of inclination 

 «! = surface angle of inclination 



Finally a value for T was calculated from: 

 T=K(S-Z)+T„ (9) 



where K = equivalent spring constant, lbs/ft 

 S = arc length, ft 

 Z = water depth, ft 

 To = initial tension, lbs 



The calculated value of T and the assvimed 

 value of T were compared, and if they were not 

 in agreement, a new value of T was assumed and 

 the calculation was repeated. The iterative proc- 



ess was continued until the assumed and calcu- 

 lated values of T agreed within a predetermined 

 limit. 



After the maximum tension in the mooring 

 had been determined, the minimum underwater 

 weight of the anchor was determined using the 

 equation : 



W=T.+ ^ (10) 



where 0.6 = assumed coefficient of friction of 

 anchor on a mud bottom 

 Ti = vertical tension, T (cos a,), lbs 

 Td = horizontal tension, T (sin aa), lbs 

 W = anchor weight, lbs 



The anchors used in 1970 were single concrete 

 blocks (5400 lbs) with 10 feet of % inch buoy 

 chain attached above each block. In 1971, Stim- 

 son anchors (4000 lbs) with 55 feet of % and 

 ly^ inch chain were iised. Portions of the chain 

 could be lifted off the bottom when the array 

 was subjected to se\'ere storms or excessive tides, 

 thereby increasing the length of the array and 

 decreasing the maximum tension which would 

 have resulted if simjile anchors had been used. 

 Thus, the possibility of failure of the array is 

 decreased. 



A Dietzgen 7410-PA Programmable Calcu- 

 lator was used for all computations. The pro- 

 grams used are reproduced in Aj^pendixes 1 

 and 2. 



