PART 6


TIDES AND CURRENTS Tides are the vertical movement of water and are caused primarily by the gravitational pull of the moon on the earth. As the moon rotates around the earth, it “pulls” the earth’s water toward it. As the moon moves, so does the water level in most bodies of ocean water. Typically there are two high and two low tides each day on the east and west coasts of the U.S. In the Gulf of Mexico there is usually only one high and one low per day. With a watch, a tide table and a chart you can determine the depth of the water in which you are sailing or anchoring at any given time.


A current is the horizontal movement of water and is caused by a river’s flow, wind, and ocean movements. The Gulf Stream off the East Coast of the U.S. is a well known ocean current. In coastal area when tides rise, currents flood; when tides fall, currents ebb. Depending on their direction, these currents can either assist or hinder your progress while sailing. It is important to know the direction and strength of currents. Charts, tide tables, and a watch are helpful in plan- ning your sail.


Current is usually weaker in shallow water


Current is


usually stronger in deeper water


Current usually runs faster through narrow openings


Tese photos, taken at the same lo- cation, show the difference between high and low tide. Consulting a tide table and a chart will help you avoid running aground during a low tide.


78


Charts courtesy Reed’s Nautical Almanac Te chart above shows tidal currents in Long Island Sound.


Currents are defined by the direction in which the are flowing. Te upper chart shows a westerly current. Te lower chart shows an easterly current.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129