I have just completed my first trip down the St. Johns River to Mayport here in Jacksonville and was sorely disappointed with the timing of the tables. On the way out we expected to find nearly a high tide while traversing the downtown lift bridges only to find falling tides the whole way to Mayport a couple of hours early. On the return trip we anticipated to go against the tide from the jetties and flow through downtown around noon with a tide shift there 'predicted' around 12:15 pm... After a 6-hour slog uphill we passed through the Main St. Bridge at 2 pm against what remained a stiff outbound current at only 2 knots over ground. Aggravating bridge tenders and impatient road traffic was not my intention. I understand that prevailing winds can stack up the flow in a body as large as the St. Johns and perhaps as well in the ocean, but the prevailing north winds that all that day should have shifted it sooner rather than later. It would seem that these tides could have been 'predicted' as well by a palm reader... Are the tide charts more or less accurate where you are? How do you accomodate the error? Are there other sources for the info than: http://co-ops.nos.noaa.gov/tides04/ or is everything based on the same data?
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Warren M.
Tide Tables
I've had some aperiodic problems with the accuracy of printed tide tables, but they have not been frequent. Last year I bought a Garmin 76 GPS and noted it has the capability to acquire and build tide data graphics from the nearest reporting station that you select (or any reporting station, for that matter). I assume this is real time data, rather than canned data that is stored and forwarded, but I'm not sure. What I am sure of, however, is that the tidal data displayed on the GPS are the most accurate data I've ever gotten.
I've had some aperiodic problems with the accuracy of printed tide tables, but they have not been frequent. Last year I bought a Garmin 76 GPS and noted it has the capability to acquire and build tide data graphics from the nearest reporting station that you select (or any reporting station, for that matter). I assume this is real time data, rather than canned data that is stored and forwarded, but I'm not sure. What I am sure of, however, is that the tidal data displayed on the GPS are the most accurate data I've ever gotten.
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Tim
I agree
My 182c seemed to always be right on when it came to tide tables. I used a printed tide table on a friends boat to go through Woods Hole and it was way off. That made for a very scary ride. Tim
My 182c seemed to always be right on when it came to tide tables. I used a printed tide table on a friends boat to go through Woods Hole and it was way off. That made for a very scary ride. Tim
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Debra B
garmin data not real-time, a computer projection
Garmin licensed a computer program (available for Palm operating system) that predicts tides based on the databases the NOAA publishes. Which is why only US waters - mostly - are covered. The tide tables I have seen published in local papers (for Tampa Bay waters) are really quite accurate. I live aboard, so I notice the tide changes every day.
Garmin licensed a computer program (available for Palm operating system) that predicts tides based on the databases the NOAA publishes. Which is why only US waters - mostly - are covered. The tide tables I have seen published in local papers (for Tampa Bay waters) are really quite accurate. I live aboard, so I notice the tide changes every day.
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Dale I
Local newspaper comparison
In comparing the tides as noted in our local newspaper to that of NOAA, they are generally within 10-25 minutes of the NOAA predictions in the correct direction but no where near what I experienced. I willl have to attempt a comparison with my Garmin 176c and do an average or typical adjustment for the area. Thanks to all.
In comparing the tides as noted in our local newspaper to that of NOAA, they are generally within 10-25 minutes of the NOAA predictions in the correct direction but no where near what I experienced. I willl have to attempt a comparison with my Garmin 176c and do an average or typical adjustment for the area. Thanks to all.
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J.B. Dyer
Garmin GPSMAP76
Warren, I have to agree with you about the accuracy of the 76. I took mine to the BVI's on a charter a couple of years ago and was amazed at way it nailed the ebb and flow of the tides there, you could almost set your watch to it and the depths were accurate also. It may or may not be real time data, but it was impressive. I keep the tide tables around but I don't look for them as often as I used to.
Warren, I have to agree with you about the accuracy of the 76. I took mine to the BVI's on a charter a couple of years ago and was amazed at way it nailed the ebb and flow of the tides there, you could almost set your watch to it and the depths were accurate also. It may or may not be real time data, but it was impressive. I keep the tide tables around but I don't look for them as often as I used to.
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Jay Eaton
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Dan McGuire
Tide Forecasts are Inexact
As most of you are probably aware, tide forecasting is not straighforward. The tide is affected tremendously by the wind and local topography. Most of the local topography such as restrictions to the flow of the water will delay the tide. The affect of wind is almost impossible to predict. As a result, any tide table can only be used as a rough guide. You must try to adjust for the other factors.
As most of you are probably aware, tide forecasting is not straighforward. The tide is affected tremendously by the wind and local topography. Most of the local topography such as restrictions to the flow of the water will delay the tide. The affect of wind is almost impossible to predict. As a result, any tide table can only be used as a rough guide. You must try to adjust for the other factors.
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