Current and Tides

[dockgoody]

I keep my boat on the St John's river in Fl but have to traverse through Jacksonville Fl to get either to the Atlantic or the ICW and/or back to my marina. Although I pay attention to tides, it appears to be a hit or miss affair catching both tide and current going in the right direction. My question is 1) whether there is either a chart one can use to coordinate tide and current, or 2) does anyone know of some type of algorithm to coordinate tide and current.

[David M]

Look in the tide and current book. Currents typically lag behind the tide in an estuary situation. There can be a significant time difference between high tide and slack water for example. The further up river you get, the greater is the difference typically.

[jackdale]

OpenCPN has tide and current data available. Have you used it? It is free. NOAA charts are also free.

[Amgine]

<big wide grin> I boat on the Salish Sea which has remarkably complex tides and currents in some places. Published data about tides and currents are educated guesses; they're usually correct, but the actual tide state and currents will always be slightly different in time, height, strength due to local variables such as winds and storms.

That said, there are many tools available to help you out if you have a computer - such as OpenCPN - which can help you figure out what to expect. You should also keep logs of what you experience so you can learn a bit every time you go in and out; compare what you really experienced with what the tide tables predicted and you may figure out that in this place the predictions are half an hour behind, or over there the currents are always the opposite of predictions (due to an eddy?). These are the kind of golden 'local knowledge' nuggets you see mentiond in Ocean Pilots and other references.