PART II: THE MODEL 

 Design Considerations 



9. Since the most important information desired from the model 

 with respect to the feasibility of construction of barriers in Warragan- 

 sett Bay concerned the effects of barriers at various locations on normal 

 astronomical and hurricane tide heights and current velocities through- 

 out the bay system (see paragraph l)^ the principal consideration in 

 design of the model was that it be capable of providing q_uantitative 

 answers to these questions^ or that the model test data be susceptible 

 of adjustment by reliable analytical methods so that the final answers 

 desired could be obtained. 



10. Since the prototype forces involved in the generation of as- 

 tronomical tides are gravitational forces^ a model for study of such 

 tides and the resulting tidal currents must be designed and operated in 

 accordance with Froude's law of similitude. Since the major component 



of hurricane tides in an inner bay system is the gravitational component, 

 the propagation of which is likewise governed to a major degree by grav- 

 itational forces, the Froude law is equally applicable to a model study 

 of this component. 



11. Model reproduction of the local wind-setup component of a 

 hurricane tide is a different matter, and this difference was discussed 

 in detail by all concerned during the planning and design phases of the 

 model study. Since simulation of wind setup in a large model such as 

 that of Narragansett Bay would be extremely difficult, time consuming, 

 and expensive, and since local wind setup can be computed with acceptable 

 acc;rracy by known analytical methods, the decision was reached that the 

 model study would be confined to investigation of gravitational phenomena, 

 and the wind- setup components would be computed by the New England Divi- 

 sion. The model was therefore designed and operated in accordance with 

 Froude's law of similitude. 



Scale Relationships 



12. The linear scales (model to prototype) selected for the model 



