Deep Zoom – Free Interactive Map for Tides and Currents
If you’re planning on fishing out on the salt, it’s essential to have an understanding of the tides and tidal current, especially if you plan on fishing from a kayak. For studying tides and tidal current, we highly recommend checking out Deep Zoom.
The main thing to not get confused about is that there are two types of guages you can click on: those for tides – the small yellow squares, and those for tidal current – the yellow arrows and/or standalone decimal numbers. The scroll bar at the bottom allows you to scroll through time to get a visual understanding of the tidal currents in an area.
There is a big difference between tides and tidal current – tides are the vertical raising and lowering of water measured in vertical feet. Tidal current, however, is the horisontal flow of water from place to place (like a river) that is a result of the tides – measured in knots (1.15 mph).
The confusing thing is that when people say “high tide”, they are sometimes refering to when the current is slack, which can be after high tide. Think of it this way: the tide is coming into a bay and the current is moving in through the mouth of the bay (aka flooding). Once it becomes high tide, it takes time for the water to actually stop because of all the momentum. When it finally stops, that is “slack” tide.
This is a simple example, whereas in real bays, there are narrows, changes in depth, and all sorts of things that affect tidal currents. This gets back to why DeepZoom is such a great tool – play around with it for a while and you will develop a much better sense of how tides and tidal current interact in the area where you are interested in going.
Things can be confusing with tides and currents… here is a real example:
Here, you can see because of the large yellow arrows that the current is going out, or west, into the ocean, out of the Columbia river (aka ebbing). On the graph on the right, you can see that it’s about noon, and the value is -4.3. This means the current is going 4.3 knots (about 5 miles per hour) OUT, shown by the direction of the arrow. Positive numbers mean the current is coming in. Negative numbers mean the current is going out. Note that on the map, the numbers remain positive because direction is indicated by the arrow. The number zero means it’s “slack tide” – there is no current.
At a nearby tide guage:
It is still about noon, and the value is 2.0. This means the tide is positive 2 feet, and does not indicate anything at all about the current speed or direction. You can see from the graph that the tide is still falling, but remember that the current will continue flowing out until after low tide, when it is finally slack low.
Unfortunately, like all weather forecasting, DeepZoom does not substitute for a general knowledge of tides and currents and knowing local conditions. For example, tidal current can combine with surface current from winds to make especially strong currents.
While DeepZoom is an excellent tool, it can definitely be somewhat glitchy. For example, when you switch from a current gauge to tidal gauge, sometimes the units for the axes on the graphs don’t change.
Anyway, I hope that some of these tools are useful if not entertaining. They’ve sure been helpful for us. Stay tuned for a similar tutorial on some of our favorite mapping websites.