26 



measurements made with the various plans installed in the model. The 

 tables show whether the base test data presented were obtained for mean 

 or spring astronomical tides. In all cases comparative plan data were 

 obtained for the same tide range as were the base test data. 

 Hurricane tide base tests 



37. Hurricane tide base test data presented in this report to 

 assist in evaluation of plan test data were obtained for one or the other 

 of the following conditions: (a) the astronomical spring tide range of 

 4.1 ft at Newport combined with the September 1938 hurricane tide; or 



(b) the astronomical spring tide range of k.l ft at NeT^rport combined with 

 the 20-knot design hurricane tide. As described above in connection with 

 the astronomical base tests^ each table presenting base test or plan test 

 data shows whether the data presented were obtained for the condition 

 described in (a) or (b) above, or both. Hurricane tide base test data 

 were obtained at the 29 automatic gage locations shown on fig. 1 for 

 each of the conditions described above. 



Technique for Testing Improvement Plans 



38. The testing of proposed barrier plans in the model involved 



some precautionary steps to insure that scale effects resulting from 



the distorted scales of this model did not adversely affect the accuracy 



of model test data, and to obtain all data required for evaluation of 



the plan in question. The detailed procedure followed in testing a 



proposed barrier plan is described below: 



a. If one or more ungated navigation openings were incorporated 

 in the design of the plan, each opening was modeled to the 

 distorted model scales and also to an undistorted scale 

 of 1:100. The openings and adjacent sections of the 

 structures were then installed in two flumes in which 

 depths were molded to conform with the depth at the loca- 

 tion of the navigation opening in the prototype. The dis- 

 torted and undistorted openings were next subjected to 

 tests covering the full range of head differentials to be 

 expected in the model, the discharge coefficients of the 

 undistorted openings were determined for each increment of 

 head differential, and the distorted openings were modi- 

 fied as required to adjust their discharge coefficients 



