The size of the arrows approximate the strength of the current
This page provides current predictions and water conditions for Grimaldo's Chair.
At Grimaldo's Chair:
The size of the arrows approximate the strength of the current
The currents here lead the tide by about 2 hours. The max flood current is 2 hours ahead of high tide, and the max ebb current is 2 hours ahead of low tide.
A positive current value (above green dashed line) indicates the current is flooding. A negative current value indicates the current is ebbing.
Many years ago, the US Department of Commerce published hourly tides for the NY harbor. These charts are displayed based on time since the last tide.
There are two relatively nearby NOAA current prediction stations at opposite ends of the waters off Coney/Brighton, which gives us a ebb/flow curve. We then take a mean of those predictions to estimate the current in our local swimming area. Note that this just provides a predicted current speed and ebb/flow. The actual direction shown here is based on local knowledge (and could be improved still!). In the absence of a closer current prediction, this seems the best approach.
NOTE! The current at our beach effectively reverses near the Aquarium (see the map). The direction of the current near the pier will be the opposite of the current at Grimaldo's.
This is an overall estimate for the area. Since it is based on NOAA current predictions, it accounts for moon phase and lunar tidal cycles. However this can not account for wind or local effects, e.g. jetty interactions.
Generally you should swim into the current at the start of your swim when you are fresh, so that you will have an easier time on the return trip. Longer swims that occur near a tide flip may want to take that into account...so the first half of the swim is with one part of the tide, and the second half will take the opposite direction.
For example, ride the flood eastward to Manhattan Beach, and the ebb on the return.