A Survey of Ship Motion Stabilization 



maximum vibration still occurred at the bow. A combination of fixed stern fin 

 and bow fin was also much less effective than a properly designed bow fin. 



Activated Stern Fins 



Spens [54,55] conducted model experiments on a MARINER class ship fitted 

 with activated stern fins and tested these fins operating singly and in combina- 

 tion with fixed bow fins. The stern fins were NACA 0012 airfoil section of 22 

 foot span and 14.75 foot chord. These fins were fitted forward of the propeller 

 as shown in Fig. 30. The fixed bow fins were similar to those fitted to the 

 COMPASS ISLAND and are shown in Fig. 31. 



After first conducting forced oscillation tests in calm water to determine 

 basic fin characteristics, controlled tests were conducted in both regular and 

 irregular waves. Table 5 presents the results of the regular wave tests while 

 Table 6 shows those test results obtained in irregular seas (fully developed 

 Newmann spectrum for 26 knot wind). These results indicate that the oscillating 

 stern fins alone perform as effectively as fixed bow fins alone. There further 

 appeared to be an additive benefit to using both sets of fins. It can also be seen 



(a) Model as towed 

 Fig. 30 - Stern fins (Continued) 



787 



