Canoeing across Coot Bay

People who live in the interior section of a country are used to rivers running in one direction. To paddle on such a river, you simply run the river in the direction of the current. However, coastal rivers that connect to bays or the ocean can flow in both directions based on tides. How far up a river the tides will have an affect depends on geology, but the closer you get to a bay or ocean, the more the flow of the river is affected by the tides. To take advantage of the situation you want to be paddling in the same direction that the river is flowing and avoid paddling when the river is flowing in the opposite direction of where you want to go.

Most people have heard of low and high tide. Each of these events mark when the water flow will change direction. As Low Tide approaches, the water is moving back out to sea and away from the mainland. If you are on the beach, you will notice that more of the sand is exposed at this time. In a bay or river, this may mean lower water levels in addition to the flow of the river running out to sea. When absolute Low Tide is reached, water flow reverses and now the race is on towards High Tide. During this time the water is flowing towards the mainland. There is less beach at this time, more water in the river, and the water now flows upriver. Once absolute High Tide is reached, the process reverses and once again the waters move out to sea.

It is easy to find the times of high and low tides. Do an Internet search for “Tides at XXX Location” and you will find the information you need. If you are at a National or State Park located near the ocean and boating is part of the park’s activities, this information will be available at the Visitor Center. However, what is more important to find out are tidal current predictions. The water just doesn’t stop flowing one way and instantly start flowing the other, nor does it flow at a constant speed. You need to find out when the water will be flowing the fastest (at which time you will want to be paddling with the flow) and when the flow is negligible and won’t have much affect on your paddling efforts no mater which way you go.

There are general “rules of thumb” as to when currents reach maximum speeds, but all depends on the type of currents that occur on a particular river. There are Standing Wave currents, Progressive Wave currents, and Hydraulic currents (only happens at a handful of locations in the USA, mainly where canals connect two bodies of water). Chances are that the park Ranger will have no idea what you are talking about if you mention these types of currents, but he will know when the water will be moving its fastest.

For simplicity’s sake, lets assume that the tide changes direction every six hours (which is close to the time when tides do change direction). With Standard currents, as high or low tide approaches, the current slows to the point that it is not noticeably going one way or another (slack tide). The fastest current will occur at the mid-way point between the high and low tides. In general, the slack tide occurs one hour before and one hour after the low or high tide. The hour prior to this (two hours before or after the low or high tide) may not be very fast either. However, the fastest current occurs during the third and fourth hour after a tidal change, the two middle hours. With a Progressive Wave current, the fastest current occurs around the low and high tide points and the slack tides occur around the mid-way points in tidal changes. To make matters more complicated, most river currents fall somewhere in between Progressive and Standing, which means every river will be different and the only way to know maximum current times is to ask somebody who is familiar with the river.

As to how current speeds and tide affect your paddling plans, lets assume that you are on a river where high tide occurs at 6 AM, that the water has a typical Progressive Wave current, and that the tides do have an affect on the water flow. I have been on some rivers that have negligible tidal effects no matter what time it is, and I’ve been on rivers where you are just wasting your time paddling against the flow, as it is so strong that you barely move. If this is the case you might as well pull over and wait for a couple of hours before proceeding.

For six hours prior to 6 AM, the water has been flowing up river and if you were trying to go downriver, you would have been paddling against the current. But now that high tide has been reached, the current direction now changes, flowing back out to sea for the next six hours until low tide is reached. If you start upriver and paddle towards the ocean at 6 AM you will have an easier time paddling because you will be going with the flow of the water.

With the Standard Current, you could paddle in either direction during the hour before and after the tidal change, and you probably won’t have much problem paddling two hours before or after the change. Thus, if you are paddling anywhere between 4 AM and 8 AM you could travel in either direction without seeing much difference in paddling effort. However, from 8 AM to 10 AM the river will be flowing back towards the ocean at its top speed. It would be great if you can paddle downriver at this time, and you surely don’t want to be paddling upriver at this time. The current speed once again slows to manageable levels between 10 AM to 2 PM, two hours on either side of the low tide mark.

The next factor that plays a part in your paddling plans is whether or not you have a ride at the end of the river or if you have to paddle back to the starting point. You must also have an idea of how many miles an hour you can paddle. For our example let’s say that you paddle 2 miles an hour and plan to paddle 10 miles of river in one direction, but you must also paddle back because you have no ride arranged, a 20-mile total (you’ll need a long summer day). Thus, the 20-mile trip will take at least 10 hours.

If you leave at 6 AM you won’t get much help for the first two hours, but from 8 AM to 10 AM you should find that the paddling is much easier. After 5 hours of paddling you will reach the end of the river, which is one hour before the current changes direction. Just as your started the trip, you’ll reach the end without much help from the tide. If you immediately turn around and head back, though you are technically paddling against the tide for the first hour, the water flow would be so slow that you can proceed without much negative affect on your paddling.

At noon the low tide is reached and now the water reverses and starts to flow back upstream, which is the direction you will be paddling. Again, for the first two hours after the change, 12 PM to 2 PM, you won’t get much help, but starting at 2 PM the water really starts to move, so for the last two hours of your journey you’ll have an easier time paddling.

Simple enough…

Unfortunately, you can’t always leave at an optimal time. Some rivers are flowing your way at 2 AM, but not at 11 AM when you finally make it to the river. In our example, if you left at 11 AM you wouldn’t have much trouble for the first three hours of the journey, but you still have two hours to paddle downriver when the tide reaches maximum speed against you from 2 PM to 4 PM. Depending on the current speed, you may find it futile to keep paddling. At one river in the Everglades, I was paddling for five minutes and didn’t make it 20 feet. At that point I just pulled over on the side of the river for two hours (I had lunch and took a nap). After two hours, despite the river still flowing against me, the speed of the current became negligible and didn’t have much effect on my efforts. The currents can become so strong that even world class paddlers cannot proceed. The fastest tidal currents in the world reach up to 9 knots (nearly 10 MPH), though most currents will be somewhere up to 3 knots (a little over 3 MPH).

Tide also has an affect on the water level. In some rivers, at low tide there might not be enough water to paddle at all (though I haven’t run into this myself). Also, the further you are up a river the less the tide will matter. The best thing to do when making a plan is to call the park and ask a Ranger about the tidal effects for both current and water level. If the Ranger says you won’t notice the effects one way or another and that there is always plenty of water, you can start at any time. Otherwise, try to plan your start time accordingly and realize that if you can’t leave at an optimum time that you may have to take up to a two-hour break until the current slows enough to make paddling once again feasible. Be sure to figure that into your plans and make sure you have enough time to get back before it gets dark.

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