Longitudinal Hull Gird^ 

 Stress at Amidships 



Heave Acceleration 

 at Center of Gravity 



Location of Stereo Cameras 



Control Center, Recorders 

 Gyro, (Pitch & Roll) 

 Pitch Accelerometer 



Midship Section Modulus (for location of strain 

 Midship Section Moment of Inertia 75X ft^ 

 Block Coefacient 0.571 



Midship Section Area Coefficient 0.972 

 Prismatic Coefficient 0.588 



Waterplane Area Coefficient 0.703 



11,000 ft-in. 



Slamming Pressure 

 Plate Strains 

 Plate Deflection 

 Acceleration at Keel 

 Strain in Keel 



Pressure Trigger 

 Switch 



Figure 1 - Profile and Characteristics of USCGC UNIMAK (AVPlO-Class Vessel) 



The information received from these officers is summarized in Table 1. These estimates were 

 primarily based on an examination of ships' logs. 



The sea conditions will be specified in terms of a significant wave height.* Estimates 

 of the significant wave heights are made by weather observers stationed on a number of weatii- 

 er ships at various locations in the Atlantic Ocean. These observations have been made at 

 3-hr intervals since 194:7. It has been found that tlie frequency distribution of these significant 

 wave heights is approximately logarithmically normal.^ The Weather Bureau's observations of 

 significant wave heights have been utilized here to evaluate the sea conditions to be expected 

 in the North Atlantic Ocean. 



During the at-sea phases, oscillographic recordings were made of actual variations of 

 roll and pitch angle, heave accelerations, and hull strains as the ship responded to wave- 

 induced loads. In general, 1/2-hr continuous records were taken for each combination of ship 

 speed, heading, and sea condition. Typical oscillograms are shown in Appendix A. Instru- 

 ments were located as shown in Figure 1. 



The pressures incident to slamming acting on the ship's bottom were measured by 

 seven pressure gages installed on the UNIMAK.^ Similar but more limited data were obtained 

 during trials^ of a sister ship, the USCGC CASCO. 



*The significant wave height was obtained by averaging the observed highest wave in each of a number of 

 groups of waves. Note that the term "significant height" as used here is not synonymous with the statistical 

 meaning of "significant" value which is defined as the average of the upper third highest values. 



