CONTENTS 



Page 



Preface: ii 



Tidal currents, general characteristics: 



Definitions 1 



Reversing tidal currents 1 



Variations in strength of current 3 



Types of reversing currents 4 



Relation of time of current to time of tide 5 



Distance traveled during a tidal cycle 7 



Duration of slack 8 



Velocity of current and progression of tide 8 



Rotary tidal currents 9 



Effects of nontidal currents on rotary currents 12 



Harmonic constants 14 



Mean values 15 



COASTAL CURRENTS, ATLANTIC COAST 



Introduction 16 



Method of observing 16 



Methods of reducing the observations 17 



Preliminary statements 17 



Nonharmonic reduction of reversing tidal currents 17 



Nonharmonic reduction of rotary tidal currents 18 



Harmonic reduction 19 



Nontidal current reduction 19 



Wind current reduction 19 



Presentation of the results 20 



Locations of stations 20 



Explanation of the tabular data 20 



Explanation of the graphic data 24 



The Gulf Stream at Diamond Shoal Lightship 24 



Current charts, Georges Bank and vicinity 25- 



Index 71 



Publication notices 75 



ILLUSTRATIONS 



Figure 



1. Current curve. The Narrows, New York Harbor 2 



2. Effect of nontidal current on reversing tidal current 3 



3. Curves of daily and mixed types of reversing currents 5' 



4. Tide and current curves, The Narrows, New York Harbor 6 



5. Rotary current, Nantucket Shoals Lightship 10 



6. Mean current curve, Nantucket Shoals Lightship 11 



7. Effect of nontidal current on rotary tidal current 13 



8. Tidal currents at lightship stations. Cape Elizabeth to Point Judith. _ 26 



9. Tidal currents at lightship stations, Montauk Point to Barnegat Bay-. 26 



10. Tidal currents at lightship stations, Cape May to Cape Hatteras 26 



11. Tidal currents at lightship stations Cape Lookout to Charleston 



Harbor 26 



12. Tidal currents at lightship stations, Port Royal Sound to St. Johns 



River 2ft 



13. Nontidal currents at lightship stations. Cape Elizabeth to Point Judith. 26 



14. Nontidal currents at lightship stations, Montauk Point to Barnegat 



Bay 26 



15. Nontidal currents at lightship stations, Cape May to Cape Hatteras. _ 26 



16. Nontidal currents at lightship stations. Cape Lookout to Charleston 



Harbor , 26 



III 



