shall we swim today? Grimaldo's Chair


This is a work-in-progress. Please don't take it too seriously yet. The goal is to provide a rough estimation of what the current is doing at a given time, and to illustrate it in a helpful way.
Feedback welcome.

Change the time: -1 hr now +1 hr

Current Prediction

At Saturday, January 22 at 9:04 AM, we estimate the current is flooding at 1.1 knots and is getting weaker.
An incoming flood tide will be going from west to east at Grimaldos Chair

Current map

Area tide chart The size of the arrows approximate the strength of the current

Tide Current Projection

Tide and Current plot 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.

Legacy Map - 5 Hours after Low Water at New York

Many years ago, the US Deptartment of Commerce published hourly tides for the NY harbor. This is the most closely matching chart, as it is 5.1 hours since the last low tide.

Historic area tide chart

Where do the current estimates come from?

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 precitions, it accounts for moon phase and lunar tidal cycles. However this can not account for wind or local effects, e.g. jetty interactions.

How is this useful?

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 the first half of the swim is with one part of the tide (e.g. ride the flood eastward to Manhattan Beach), and the second half will take the opposite (e.g. riding the ebb on the return).