Giddings and Wermter 



Fig. 25 - Comparison of various mathematical 

 models with experiment 



must be involved in any further magnification of this damping. It is quite im- 

 practical to generate these large forces by means of internal devices generally 

 associated with roll stabilization, i.e., tanks, gyros, moving weights. To further 

 complicate the problem, the pitch phenomenon is not resonance dominated as is 

 roll, that is to say, the roll spectrum is sharply tuned while pitch responds to a 

 broad range of frequencies. 



Thus, all attempts at pitch stabilization have been through the use of exter- 

 nal devices, capable of sustaining the large forces involved. These devices have 

 been fixed bow fins, moveable stern fins and to a lesser degree moveable bow 

 fins and fixed stern fins. Only the fixed bow fins have been installed on ships, 

 these installations being made on the RYNDAM of the Holland- American Line 

 and the American ship COMPASS ISLAND. While considerable pitch reduction 

 was achieved in both cases, a severe horizontal bow vibration associated with 



776 



