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#1 The times of minimum before flood and ebb are indefinite.
#2 Current speeds up to 9.0 knots have bee observed in the vicinity of the Boilers.
#3 Current turns westward just before the end of the flood.
#4 Current tends to rotate counterclockwise, flood direction swinging from westward to southward.
#5 Observations indicate that current floods about 11 hours and ebbs about 1 1/2 hours. Minimum before flood occurs about 4 1/2 hours earlier, maximum flood about 1 hour later, minimum before ebb about 1/2 hour later, and maximum ebb about 1 1/2 hours earlier than corresponding predictions at Portsmouth Harbor Entrance. Average ebb speed is less than 0.5 knot.
#6 Current is variable; current speeds are usually less than 1 knot. Currents are strong in the entrance to Menemsha Pond.
#7 In the open waters of Buzzards Bay, except in the entrance and off Penikese Island and West Island, the current is too weak and variable to be predicted.
#8 The currents in Narragansett Bay have a pronounced irregularity which is evidenced at times during the month by a long period of approximate slack water preceding the flood, and at other times by a double flood of two distinct maximums of speed separated by a period of lesser speed. These peculiarities appear to be somewhat unstable, consequently, flood currents differing from those predicted should be expected. The ebb current is fairly regular and the predictions for maximum ebb will usually agree closely with the current encountered.
#9 At minimum flood, current sometimes ebbs for a short period.
#10 At minimum flood, current frequently ebbs for a short period.
#11 Flood is too weak to be predicted. Time difference gives mid-point of 4 hour stand of weak and variable current and time of maximum ebb.
#12 Inside breakwaters, in channel, the current is only 0.4 knot.
#13 Current seldom floods.
#14 Near Tongue Point, Bridgeport Harbor, the current is weak and irregular.
#15 Tidal Current is weak, averaging about 0.1 knot at maximum.
#16 For maximum southward current only, the gates of the lock being closed prevent northward flow. Apply difference and ratio to maximum ebb at The Narrows.
#17 The values for the Hudson River are for the summer months, when freshwater discharge is a minimum.
#18 In Roundout Creek entrance between lights, eddies on the flood make navigation difficult. Little difficulty will be experienced on the ebb.
#19 Current does not flood.
#20 Current is rotary, turning clockwise. It flows northwest at times of "Minimum before flood" at The Narrows; northeast 1 hour after maximum flood; southeast 1 1/2 hours after "Minimum before ebb"; and southwest 2 hours after maximum ebb.
#21 Current is rotary, turning clockwise. Minimum current of 0.2 knot sets west about the time of "Minimum before flood" at The Narrows. Minimum current of 0.2 knot sets east Northeast about the time of "Minimum before ebb" at The Narrows.
#22 In Sandy Hook Bay (except in southern extremity) the current is weak.
#23 Tidal current is weak and rotary, averaging about 0.1 knot at maximum.
#24 The times of minimum before flood and ebb are variable.
#25 Current usually ebbs during period 3 hours before to 2 hours after maximum ebb. Flood is weak and variable.
#26 To obtain speeds in mid-channel use speed ratio of 0.8.
#27 Flood is usually weak and of short duration. A weak ebb current occurs about 6 hours after maximum flood at Delaware Bay Entrance.
#28 Tidal current is weak and rotary, averaging less than 0.1 knot.
#29 Current tends to rotate clockwise. At times for "Minimum before flood" there may be a weak current flowing west southwest, while at times for "Minimum before ebb" there may be a weak current flowing north.
#30 Current tends to rotate clockwise. At times for "Minimum before flood" there may be a weak current flowing southwest, while at times for "Minimum before ebb" there may be a weak current flowing north.
#31 Flood usually flows northward, however, direction is variable.
#32 Flood is variable, current sometimes changing to ebb for a short time during the flood period.
#33 Due to changes in the waterway, average speed values given are probably too large.
#34 Flood usually occurs in a southerly direction and the ebb in a northeastwardly direction.
#35 Flood is weak and variable.
#36 Current tends to rotate clockwise. At times for "Minimum before flood" there may be a weak current flowing northward while at times for "Minimum before ebb" there may be weak current flowing southeastward.
#37 For greater ebb only.
#38 The strength of flood is usually about 2 knots. The speed ratio for strength of ebb is 0.8, except for an ebb speed at Tampa Bay entrance less than 1 knot or marked with an asterisk. In this case take the ebb speed at Johns Pass to be about 1 knot.
#39 For greater ebb. Lesser ebb is almost equal to greater ebb.
#40 Currents are materially affected by winds.
#41 Current is weak and variable. Current is somewhat rotary turning clockwise.
#42 Current is normally weak and variable, but winds may cause heavy swells.
#43 Minimum ebb is extremely weak, possibly flooding for a short period.
#44 Every other ebb phase exhibits a double ebb pattern. For single ebb phase use time differences and speed ratio of the first ebb.
#45 Ebb is weak and variable.
#46 Current is somewhat rotary, speed seldom exceeds 0.3 knot.
#47 Flood is weak and variable with speeds less than or equal to 0.2 knot. Minimums are indefinite.
#48 Diamond Island Pass - ebb current is very weak, averaging less than 0.1 knot.
#49 During period observed, the current flow was nearly continuously in a southwesterly directions with an average speed of about 0.4 knot.
#50 Observations during the spring showed an increase of about 0.4 knots in both the flood and ebb directions.
#51 Observations were made during the summer months when freshwater discharge was at a minimum. Periods of heavier discharge will increase ebb current speeds and decrease flood current speeds.
#52 Observations were made in the spring during periods of heavy freshwater discharge. Periods of lesser discharge will decrease the ebb current speeds and increase flood current speeds.
#53 Observations at this location showed long periods of minimum currents and short durations of flood and ebb currents.
#54 Turbulence with hazardous current speeds of 6 to 7 knots have been reported near the bridges in the canal. Extreme caution should be exercised.
#55 The time of minimum before flood is indefinite.
#56 Maximum ebb time difference is for middle phase. Speed near 0.7 knot throughout most of the ebb phase. Speeds a short distance away may vary significantly.
#57 Maximum flood time difference is for middle phase. Speed is very low throughout most of flood phase.
#58 It has been reported that under conditions of extreme river discharge, the current can reach 7 ot 8 knots. Caution should be exercised when docking and undocking vessels.
#59 In the narrow part of Woods Hole Passage (Woods Hole, 0.1 mile SW of Devils Foot Island) the current velocity at times exceeds 4.5 knots. Velocities as high as 5.0 knots have been reported by the U.S. Coast Guard. Currents in Woods Hole passage computed from the daily predictions at Cape Cod Canal in the Tidal Current Tables, should be used with caution. These differences result from dredging, filling, shoaling and other modifications since the 1931 survey.
#60 Depths at the locations were previously averaged. The original data has been separated into it component depths.
#61 The time of minimum before ebb is indefinite.
#62 Short term observational data taken by United States Power Squadrons (USPS) as part of the NOS/USPS Tidal Current Predictions Quality Assurance Program has shown that predictions at this location are accurate.
#63 Short term observational data taken by United States Power Squadrons (USPS) as part of the NOS/USPS Tidal Current Predictions Quality Assurance Program has shown predictions at these locations to be inaccurate.
#1 It is reported that an eddy is usually encountered along the ends of the municipal piers which makes docking difficult.
#2 San Pedro Channel, 7 miles south of Los Angeles Harbor Breakwater. There are two periodic currents here both of which are rotary, turning clockwise, and rather weak. The tidal current has a speed at strength of about 0.2 knot. The other current, due apparently to daily land and sea breezes, has a period of 24 hours and an average speed of about 0.2 knot. The greatest speed during the 5 month of observations was 1.5 knots. Currents greater than 1.0 knot occur infrequently.
#3 In Los Angeles and Long Beach Harbors, the tidal current is weak. Currents can exceed 1 knot in the outer harbor at San Pedro, under strong wind conditions. Also, it is reported that three minute surge waves are responsible for major ship movements and damage.
#4 Observations indicate ebb is very weak.
#5 Large Current eddies which cause ships to sheer off course are reported near the foundation piers of Gold Gate Bridge and San Francisco - Oakland Bay Bridge.
#7 Current is somewhat rotary, turning clockwise.
#8 Slack Water Time Differences for Places Along San Francisco Piers:
Beginning of Station or Locality Latitude Longitude Flood Ebb St. Francis Yacht Club breakwater 37 48.5 122 26.5 -0 10 -1 50 Aquatic Park, 0.2 mile west of 37 48.6 122 25.7 -0 35 -2 05 Pier 37 37 48.6 122 24.5 -1 35 -2 20 Pier 29 37 48.4 122 24.0 -1 10 -2 20 Pier 7 37 48.0 122 23.6 -0 55 -2 05 Pier 14 37 47.7 122 23.3 -0 55 -3 00 Pier 26 37 47.4 122 23.0 -1 40 -1 50 Pier 38 37 47.0 122 23.0 -0 25 -2 25 Pier 50 37 46.4 122 22.8 -1 40 -2 20 Bethlehem Pier No. 8 37 45.6 122 22.7 -1 20 -1 55 Pier 90, 0.5 mile SE of 37 44.5 122 22.4 -1 50 -2 05 Point Avisadero 37 43.7 122 21.3 -1 25 -0 40 Point Avisadero, 0.8 mile south of 37 43.0 122 21.5 -1 30 -3 25
#9 Current is somewhat rotary, turning counterclockwise.
#10 Current is somewhat rotary, turning counterclockwise. 4h 25m prior to computed maximum flood the current flows southward with a speed 0.6 of the flood speed at the reference station.
#11 Data do not apply during freshets.
#12 Data do not apply during freshets.
#13 Data approximate.
#15 The Columbia River bar can be very dangerous because of sudden and unpredictable current changes accompanied by breakers. It is reported that ebb currents on the north side of the bar attain speeds of 6 to 8 knots and that strong NW winds sometimes cause currents that set north in the area outside the jetties. In the entrance, the currents are variable and may reach a speed of over 5 knots on the ebb while the flood speed seldom exceeds 4 knots. The tidal current in the river is always modified by the river discharge, sometime to the extent that the flood current is indiscernible and the current ebbs continuously.
#16 Flood and minimum current data indeterminate.
#17 Observations indicate that the current ebbs continuously at this location. Data are given for the smallest and largest mean ebb values expected. The time differences and speed ratios should be applied to the predicted times of maximum ebb at the reference station.
#18 During period of observations (February) flood was weak, and current was ebbing most of the time with a speed of about 2 knots at times of maximum.
#19 Along the west coast of Vancouver Island the current is reported to set always northwestwards. It is weakest during westerly winds and strongest with easterly winds, being about 1 knot in moderate weather.
#20 When predicted flood at Admiralty Inlet, Race Rocks, or Strait of Juan de Fuca Entrance is marked with an asterisk (*) the flood speed and the preceding and following slacks at stations referred to them cannot be predicted. The current at most of these stations, however, will be weak at such times. Exceptions are the stations whose speed ratios are footnote references.
#21 Current is rotary, turning clockwise.
#22 Time of minimum before flood is indefinite.
#23 Observations indicate that current is weak with direction variable for the greater part of the tidal cycle. A maximum flood speed of 1 knot in a southerly direction has been observed.
#24 Time of minimum before ebb is indefinite.
#25 Slacks are indefinite. The flood current is weak and variable, possibly ebbing at times.
#26 Current ebbs continuously. Maximum ebb, +5h 15m; minimum ebb, -1h 20m.
#27 Flood speed at strength probably does not become less than a knot.
#28 Current is rotary and erratic. Speeds of 3 knots may be encountered.
#29 Current ebbs most of the time. The difference is for maximum ebb only. Weak current, flood or ebb, usually occurs about 0.8 hour after the maximum flood at The Narrows.
#30 Current floods most of the time. Time difference is for maximum flood only. Weak ebb or slack water usually occurs about 1 hour before maximum ebb at The Narrows.
#31 Current ebbs most of the time. The difference is for maximum ebb only. Weak flood or slack water usually occurs about 1 1/2 hours after the maximum flood at The Narrows.
#32 Current floods most of the time. Time of minimum before flood is indefinite.
#33 Close to the east shore the flood speed is reduced about 1/2 but the ebb speed is only slightly less than at Point Evans.
#34 On the west side the speed of the flood current is 0.6 that of midstream and the ebb begins about 1 hour and 15 minutes earlier. On the east side the current is about the same as midstream.
#35 Current ebbs most of the time. Time difference is for maximum ebb only. Weak flood or slack water usually occurs about 1 hour after maximum flood at The Narrows.
#36 Current ebbs most of the time. Time difference is for maximum ebb only. Weak flood or slack water usually occurs about the time of maximum flood at The Narrows.
#38 Current ebbs most of the time. Time difference is for maximum ebb only. Weak flood or slack water usually occurs about 1/2 hour after maximum flood at The Narrows.
#40 When predicted flood at Admiralty Inlet or Rosario Strait is marked with an (*) the flood and preceding and following slacks at stations referred to them cannot be predicted. The current at most of these stations, however, will be weak at such times.
#41 Ebb current is irregular at times.
#42 Current is predominantly non-tidal, flowing in a northwesterly direction with a maximum speed of 1 knot.
#43 Current ebbs most of the time. Time difference is for maximum ebb only; slack times are indefinite and flood current is weak and variable.
#44 Time difference is for maximum flood only; slack times are indefinite and ebb current is too variable to be predicted.
#45 Dangerous eddy current and tide rips are reported to occur between Helmcken Island and Ripple Shoal around the time of ebb strength.
#46 On the flood, the streams coming from the sea through the north and south entrances meet off Evening Point (Lat 53 39N) and separate on the falling tide about a mile farther northward.
#47 Observations indicate that current usually flows WNW, speed varying from zero to an average strength of 0.3 knot which occurs about 1 hour after time of maximum flood at Wrangell Narrows.
#48 Lewis Point to Guard island - Current too weak to be predicted.
#49 Observations indicate that current usually flows NW, speed varying from zero to an average strength of 1.2 knots which occurs about 45 minutes before time of maximum flood at Wrangell Narrows.
#50 Observations indicate the current usually flows NW, speed varying from zero to an average strength of 0.7 knot which occurs about 2 1/2 hours after time of maximum flood at Wrangell Narrows.
#51 Slacks occurs for a period of several hours before maximum current.
#52 Current usually flows WSW; speed varies from zero to an average of 1.1 knots occurring about 1h 05m earlier than time of maximum ebb at Wrangell Narrows.
#53 Slacks are indefinite. Flood current is too weak or variable to be predicted.
#54 Minimum before flood, 2h 41m before maximum flood; minimum before ebb, 3h 46m before maximum ebb.
#55 Lesser ebb, +0h 50m. The greater ebb may reach a maximum speed then decrease slightly for about 1 1/2 hour before increasing to a second maximum. These time differences are 1st maximum, -0h 42m; minimum +0h 43m; second maximum, +1h 32m; and are referred only to the greater ebb phase at the reference station.
#56 Current too weak and variable to predict.
#57 Observations indicate that the current flows WNW with a non-tidal current of 0.6 knot.
#58 Currents are materially affected by winds.
#59 Northeast of Lively Island, it is reported that the current sets constantly northwestwards, being stronger when the main stream west of the island sets northwestwards.
#60 In the section of El Capitan Passage west of Dry Pass the current turns westward about the time of the strength of eastward current in Dry Pass, and turns eastward about 1 hour before the time of strength of westward current in Dry Pass.
#61 Time difference is for maximum ebb only. Flood current is very erratic.
#62 Current frequently ebbs throughout the day, especially when moon is in quadrature.
#63 Slacks before flood may be variable.
#64 Observations in Fredrick Sound during summer months indicate that the current usually flows northwestwards, the speed varying with the tide. It apparently southeastward on very large tides.
#66 The currents in Nawasina Passage, except at the location 1 1/2 miles west of Allan Point, are too weak and variable to be predicted.
#67 Slacks are undetermined.
#68 Current is erratic in direction and strength at times.
#69 It is reported that currents are strong and passage is navigable only near time of slack water.
#70 Observations indicate the current usually flows northward, speed varying from zero to an average strength of 2 knots which occur about 2.3 hours before time of maximum flood at North Inian Pass.
#71 A weak ebb probably occurs at this station when flood speed at North Inian Pass is less than 2 knots.
#72 It is reported that currents are strong and passage is navigable only near time of slack water.
#73 Observations indicate that current usually flows eastward with an average speed of 0.8 knot.
#74 It is reported that close inshore at Anchorage an eddy current flows up Knik Arm during the ebb.
#75 The tidal currents in this strait are weak except at the Slough and the Narrows where the speed at strength may amount to 2 or 3 knots on large tides.
#76 Current is rotary, turning clockwise. Minimum current about 0.1 knot, setting 160 True.
#77 Off Whirl Point, the speed of the current is about twice that off the Cannery.
#78 Dangerous tide rips occur in most passes in the Aleutian Islands when sea and swell oppose strong currents.
#79 Tidal current is weak and rotary, turning clockwise. Observations indicate a 0.2 knot westerly set.
#80 Ebb speed may not exceed 5.5 knots.
#81 When predicted ebb speed at Akutan Pass is less than 2 knots the current at this station is weak and varaible.
#82 When predicted ebb speed at Unimak Pass is less than 1 knot the current at this station is weak and variable.
#83 Flood begins 1 hour before maximum ebb at Unimak Pass.
#84 The current at this station changes direction abruptly and the time of change is unpredictable. Maximum flood occurs about 10 minutes earlier and maximum ebb about 55 earlier than the corresponding currents at Isanotski Strait. Usually there will be a strong current during the period 1 1/2 hour before to 1 1/2 hour after the predicted times of maximum flood and ebb.
#85 Ratios are for greater flood and greater ebb only. The flood and ebb inequalities are small when the moon is near the equator. At other times there is considerable difference between the two floods and also the two ebbs in a day. The lesser flood may even become a small ebb at extreme declinations.
#86 Time difference for greater ebb and slack before greater ebb. Slack before greater flood and greater flood occur 7 hours and 12 hours respectively after greater ebb. Current floods for about 8 hours after greater flood.
#87 Flood speed ratio is for the 1st flood after greater ebb; the ebb speed ratio is for greater ebb.
#88 For greater flood and greater ebb only. The current is rotary, turning clockwise. At the predicted time of slack before greater flood, the current will run westward with speed of about 1.5 knots. At the predicted times of all other slacks and also lesser flood and lesser ebb (or minimum flood), the current will run northward with speed of about 1 knot.
#89 Current is rotary, turning clockwise. About 5 hours after time of greater ebb at Unimak Pass, current flows NW, speed ratio 0.4 and about 13 hours after the greater ebb an Unimak Pass, current flows SE, speed ratio 0.5.
#90 Current is somewhat rotary, turning clockwise and is too variable to be predicted.
#91 Current is somewhat rotary, turning clockwise and is subject to considerable fluctuation. Approximate predictions are obtained through the following relations to greater ebb at Unimak Pass: +1 1/2 hours, sets SSW, ratio 0.8; +9 hours, weak probable weak northerly set; +18 hours, sets NNE, ratio 0.6.
#92 Current is weak and rotary, turning clockwise. Data is for the greater ebb which is the most consistant phase.
#93 Current is somewhat rotary turning clockwise. At times given for slack, flood begins and slack, ebb begins the current probably flows WNW and ESE respectively, with speed of about 1.5 knots.
#94 The current changes from ebb to flood abruptly and predictions for beginning of flood are approximate.
#95 Maximum flood 1 knot greater and maximum ebb 0.5 knot greater than corresponding speed at Kvichak Bay.
#96 Current is rotary turning clockwise. At the predicted times of slack before flood or ebb the current will run westward or eastward respectively with speed about 0.2 knot.
#97 Current is rotary turning clockwise. Difference and ratio are for maximum flood current only.
#98 Current is rotary turning clockwise. Midway between flood and ebb current in minimum (about 0.2 knot).
#99 Current is rotary turning clockwise. An average maximum speed of about 0.7 knot occurs in a SSW direction.
#100 Current flows in an ENE direction with an average speed of 1.1 knots. All values appearing in the ebb column are actually those for a minimum flood.
#101 Time differences are for slack before greater flood, slack before greater ebb, and greater ebb. maximum flood occurs about halfway between the times of the slacks obtained through differences. Speed ratios are for greater flood and greater ebb.
#102 Observations indicate that the current usually flows NNE with an average speed of 0.3 knot. Values in the ebb column are actually those for minimum flood.
#103 Observations indicate that the current flows in a northerly direction with an average speed of 0.6 knot. Values in the ebb columns are actually those for a minimum flood.
#104 Observations indicate that the current flows in a NNE direction with an average speed of 0.9 knot. Values in the ebb columns are actually those for a minimum flood.
#105 Observations indicate the existence of a permanent current setting north with an average speed of 0.7 knot. Combined with the tidal current, the northward current may have an average speed varying from slack to 1.4 knots. The greatest observed speed off Maui Island was 2.7 knots.
#106 Observations indicate the current usually flows northwest on the west side of the channel near Kahoolawe Island with a maximum speed of 0.7 knot.
#107 Observations indicate that current usually flows SSE on the east side of channel near Maui Island with a maximum speed of 0.4 knot.
#108 Current seldom floods. It decreases from maximum ebb to a minimum ebb or slack, then increases to maximum ebb again with no significant flow in the flood direction.
#109 Current sets northeast with an average speed of about 0.3 knots.
#113 Current flows continuously in a westerly direction. Differences are for mean maximum speed.
#114 Current ebbs continuously. Differences are for mean maximum ebb only.
#115 Current floods continuously. Differences are for mean maximum flood only.
#116 Slacks are indefinite. Flood current is weak an variable. Differences are for mean maximum ebb only.
#117 Minimum before flood is indefinite. Flood is weak and variable.
#118 Weak and variable current ebbs continuously in a southeasterly direction.
#119 Slacks are indefinite. Flood current is weak and variable. Differences are for a small ebb current.
#120 Current ebbs continuously with speeds varying from 0.7 knot (shown in maximum flood column) to 1.5 knots.
#121 Due to distrubances caused by the structure, observed currents within 50 feet of the pier can be significantly different from the predictions.