chambers alone is sufficient. Equation (1) may be used to estimate the 

 reserve buoyancy provided by a clean single-pipe PT-1 module if some terms 

 are redefined : 



F = F se H = sediment and biofouling load (per tire) 



F = extraneous load (from binding material, tire retainers, pipe end 

 caps, shackles, etc.) 



F = buoyancy force due to entrapped air (for each tire not foamed) 



Ff = buoyancy force due to submersed foam (for each tire that is foamed) 



n = number of tires per module 



m = number of tires foamed (per module) 



This leads to 



nF BeH + nW,.„ + F e = F n + (n - m) F a + mF f 



(2) 



= (F„ " W,„) +(-) (F n - F ) +(-) (F f - F) 



Using the following approximate values and estimates for the PT-1 module: 



F e = 220 kilograms 



F = (60 kilograms per meter) (12 meters) = 720 kilograms 



W tw = 7 kilograms 



F fl =17 kilograms (50 percent of value from buoyancy test) 



Ff = 34 kilograms (crown fully foamed, 34 liters) 



n = 176 tires 

 to obtain 



F sed " < 17 " 7 > + 



\ 1/ D / \ n / 



(^) (72 °- 280>+ G) (34 - 17) 



G) 



? sed = 13 + 17 ( - ] (kilograms per tire) 



22 



