Tides & Currents 101
Perhaps the most significant factor in turning your paddle hobby into a passion / regular activity is overcoming the information hurdle of the Bay’s tides and currents. New paddler’s are intimidated by, while experienced paddlers are respectful of, the legendary force the fills and drains this massive basin twice daily. It’s not complicated to understand the science of tides and currents, but it takes some thought to apply the practical lessons to your paddle habits. Let’s dive in (yup, I did that).
TIDES
The easiest way to think of this is that Tides are the rising and falling of the sea level, while the currents are the force of said rising and falling. Another way to think of it is that tides go up and down, currents pull side to side. So, when we speak of tides, we’re referring to the meticulously tracked movements linked to the phases of the moon and sun. We really don’t need to dive into the science behind these forces, though you can read more about them for yourself. What we’re concerned about is how they effect our paddling and how to read them.
CURRENTS
Currents are the force which the tides generate as they move water in and out of the Bay. The force of the current depends on multiple factors. The most significant factor is the stage of the tide at any given moment. The easiest way to think about this is to imagine that each time the Bay fills up, water from the ocean surges in a (flood) force into the Bay, and exits (or ebbs) with similar force. If you can imagine, this force is strongest in narrow sections (under the GG Bridge for example in red below) and at the peak of momentum between the shifting between high and low tides. At transition points – just before and after low or high tide, the force has to slow down and shift in order to reverse itself. The periods when this shift occurs is called “slack tide or current”. During a slack tide, the momentum slows, we hit high or low tide, and the energy starts to flow in the opposite direction. Generally speaking, we usually call slack tide approximately one hour before or after both high or low tide. This is not exact, but works as a rule of thumb.
Now, while this gives you the direction and relative current force within the phases of the tides, this does not give you any information about the objective force of the current. There are periods where you might be in the peak of a flood current and the water is like a lake while other times it can suck even the strongest paddler out to sea. NOAA / Tides Near Me offers a measure of the flow of the current by way of the relative height of the highs and lows which has a direct correlation to the volume of water entering or exiting the Bay. You can expect that if there is a particularly high tide (especially during the King Tides we’ve been experiencing) the volume of water is greater, which will likely create more force in current.
But the best measure of current force is going to be your experience and judgement. There is no paddle plan that cannot be upended or revised. If you are on the water and you reach the ends of the piers or dry dock (where we have warning markers on our map) and you are being pulled at a rate that is unmanageable, you have two options (1) if you planned to go WITH the current, have a blast and have a plan to pull out down the line where you’re headed (2) don’t go too far out before you realize the force so that you can paddle hard back AGAINST the current to the inlet on the other side of the warning point. You’ll find the currents much gentler on the inner side of Pier 50, Pier 80, the Dry Dock, and McCovey Cove.
To that point, beginners should NEVER go past our warning points on our map until they are comfortable knowing how to read the current and strong enough paddlers to compensate for the unpredictable. The area in front of Crane Cove is a calm proving ground for your skills. Intermediate paddlers can travel up and down the shoreline between Crane Cove and Pier 54 without encountering the strongest forces of the Bay. Make sure you’re confident before you head out past the check points, and always plan ahead.
HOW TO READ THE TIDES
The National Oceanic & Atmospheric Administration (NOAA) publishes very detailed schedules of the tides on their site. We like the app “Tides Near Me” for presenting them on the iPhone or Android. For Crane Cove Park, you want to search up the “Potrero Point” station as a reference point. You will see the daily highs and lows. When you’re planning a paddle, the best way to think about your route is: (1) when am I planning to leave (2) when will I be returning, and (3) what phase of the tides will be occurring during this time. Generally speaking, we prefer to paddle in a slack tide or against a light current on the way out and have the current at our back on the way home. This way you can go all-in on the way out, and be safe on the return (you can still paddle hard with the tide, but you won’t be fighting it, in case you’re gassed).
For example: Let’s say that low tide is at noon tomorrow and I want to go from Crane Cove to Mission Creek Dock, passing the Cape Horn / Hudson and McCovey Cove. The trip takes approximately one hour at a reasonable pace, each way. Therefore you want to leave some time around 11am, which would be the start of the ebbing slack period, giving you a gentle push at your back. Then, after an hour it would be low tide, starting to shift into flood tide. There would be a gentle slack against you as you paddle from Mission Creek to McCovey Cove, but when you hit the crux of the journey and open water, you would have the current at your back from Pier 48 all the way to Crane Cove.
For shits and grins: If you wanted to go in the other direction, south? You guessed it, think high tide / slack. Leave Crane Cove an hour before high tide towards the Dry Dock and Pier 70. Paddle for an hour or more in the slack so that when you return you’ll be in the ebb phase with the current to your back.
GET EXPERIENCE
The best way to learn is to go with people who have spent time exploring and are willing to share. Our Facebook Group is a great place to make paddle connections. Find a partner who is looking to pair up and share their knowledge. Or take on of our lessons. Every Sunday we offer sessions for beginners at 11am and intermediate paddlers at 1pm. Here you can pick up stroke & stance technique and gain confidence as you follow our experienced guides into the conditions of the day. We look forward to seeing you on the water and are happy to help you plan safe and enjoyable experiences.