minimized by conducting the tests for a given sea state during one continuous time interval 

 with the exception of the data for the State 3 Sea, for which two different time periods were 

 required. The estimates of the sea state, as defined by the scale given in Reference 4, 

 were made by the Weather Bureau observers who were assigned to the USCGC UNIMAK during 

 the trials. In order to give a more quantitative idea of the sea state, sample stereophotographs 

 together with photogrammetric analyses thereof are reproduced in Appendix C for sea states 

 experienced during the trials of the UNIMAK (States 2, 4, and 5). 



Inasmuch as the evaluation of sea states made by ships' officers and reported in Table 

 1, as well as that made by weather observers during the sea tests, depended upon visual ob- 

 servations, one may expect reasonable agreement in the severity of the sea as defined by the 

 sea state. In any case, no better basis for making the synthesis given in Tables 8 tiirough 11 

 was available to the authors. 



The general method of synthesis utilized in this report could also be applied to data 

 obtained from model tests of ships in waves rather than from full-scale test data. This would 

 be a more flexible arrangement in that a wider variety of conditions could economically be 

 covered by model tests than would be feasible with full-scale tests. Furthermore, the problem 

 of measurement would be less difficult. 



The order of magnitude of the pressures measured on the USCGC UNIMAK were also 

 experienced by a sister ship, the USCGC CASCO (formerly AVP 12), during earlier sea tests 

 in 1951. The indications are that the measured pressures are typical of the loading to be ex- 

 pected in heavy seas for this type of ship, 



ACKNOWLEDGMENTS 



The cooperation of the Commandant, U.S. Coast Guard and the Commanders, Air Force, 

 U.S. Pacific and U.S. Atlantic Fleets made it possible to obtain realistic operational esti- 

 mates of the speeds and headings under which ships of the AVP class are expected to operate 

 in service. The NaVal Photographic Interpretation Center and the Naval Hydrographic Office 

 made the analyses of stereophotographs given in Appendix C. Mr. B.M. Wigle of the Vibra- 

 tions Division, Taylor Model Basin, assisted in the calculations. 



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