VARIABLE 



BALLAST 



PUMP 



TRIM (AND V B T) 

 TANKS 



MAIN 

 BALLAST 



Fig. 6.12 Trim system components of BEAVER (top view). 



Oil Transfer: 



The trim system of DOWB is not so much a 

 transfer of weight function as it is a displace- 

 ment function. It consists of a central trim 

 tank within the pressure hull, a fore and aft 

 trim bladder and a hydraulic trim pump with 

 associated valves, piping and fittings (Fig. 

 6.13). By transferring oil between the blad- 



ders, to decrease or increase fore and aft 

 displacement, an up/down bow angle of 2.5 

 degrees can be obtained. 



With such ballast and trim systems at his 

 disposal, the operator of a submersible at- 

 tempts to carry out his mission. Some mis- 

 sions, however, provide options to frequent 

 adjustments in ballast or trim. When a vehi- 



PRESSURE HULL 



AFT 



TRIM 



BLADDER 



FWD 



TRIM 



BLADDER 



HYDRAULIC 

 TRIM PUMP 



Fig. 6.13 Trim system components of DOWB (starboard side view) 



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