need some help estimating tidal shift

Advice
#1

Living in wv I’m mostly an inland paddler but occasionally hit up coastal waters. I Prefer protected areas like smallers bays and tidal creeks. Generally I avoid open water. I don’t have that skillset. I’m trying to learn about tidal timing and use it to propel my short boats.

I did pretty well in Maine this summer. Spent an afternoon paddling down some very low (push with your hands/paddle) ww on Denny’s River. My paddlin’ bud and I then proceeded to paddle the tidal section of the river and went to the reversing falls in Cobscook bay. That was pretty well timed out as we ran with the tide and had plenty of water.

More recently, I was less successful with timing the tides. In South Carolina I put in on Rantowles CreeK (trib of Stono River) at bulow landing. My plan to was ride the tidal shift down (low tide) and then head back (high tide). As it turned out, I floated the low tide but had to actively paddle back against it or risk running out of daylight. I consulted a charleston harbor tide chart (instead of the wallace creek/rantowles chart which I found online after i got home). But to be fair, I didn’t hone in on Rantowles until I saw its proximity to the campground where I was staying. Internet was sketchy. Even without the more local beta it seems to me I should have better able to anticipate the tidal lag of the upstream location. Perhaps if I had figured the distance from charleston harbor, the size of the tide and the time between low and high tide then I could have better anticipated the timing of the shift . Perhaps elevation should be a factor as well?

****Are there some simple formulas folk use to anticipate tidal shift at specific locations when your tide beta is for a different location? ****

#2

Well if you have tide tables for two locations that bracket the location you can guestimate when high and low tide are … the problem with tides is you have to know about how much the wind affects the water movement and the volume of water that is stacked up inland and what kind of constrictions with local channels and Islands effect it. So in a word you can guess but more often than not you need some experience at many different tide levels and wind conditions for the place you are paddling.

#3

It’s hard to beat local knowledge to supplement a tide table for somewhere nearby. As an example, we were paddling off Gilford Island in the Broughton Archipelago last summer. Inquiring locally, I learned that we would be in an area that was about 40 minutes later than the Alert Bay tide table - usable information. Rivers and estuaries make things more complex, so local knowledge becomes more important.

#4

Local knowledge is key, as there are variations. For example, if you are on a river, the current of the river will play into the strength and timing of the tidal currents. About 10 years ago I paddled the Columbia River from Bonneville Dam to ocean, and was disappointed that I couldn’t get current estimations. Flatpick (long time member here, but not too active any more) clued me in - the currents were more based on the river flow, and that was based on the power needs and how much water was going through the generators. Currents were stronger during week, and weaker on weekend. And above Longview (~100 miles below Bonneville Dam), it was always a downstream current, just varying how much based on tides and river flow (even though the river height changes due to tides all the way up to Bonneville Dam).

And get the tide info for as close to the area you are at as possible.

This said, some guidelines that hold for many areas:

If you have tide estimations for one area, but need for another area somewhat nearby - if the area is closer to the ocean, the tidal cycle will be earlier. If further from ocean, it would be later. On the Columbia River, 20 miles further inland was 1 hour delay in tides. SF Bay seems to run an hour difference for 15 or so miles of distance.

In general tidal currents lag the high/low tides. In my area, they lag by about an hour (so 1 hour after low tide would be low slack - if high tide was at noon, the high slack would be at 1).

From low slack to high slack (or visa versa) is a 6 hour cycle. Hour 0 is slack water, hour 1 is 50% of max ebb or flood current speed, hour 2 is 90%, hour 3 is max current speed, hour 4 is 90%, hour 5 is 50%, hour 6 is slack. So if you can get max flood or ebb current estimations, you can estimate the current speeds at other times.

Another caveat - info above is for area with 2 high tides a day (what most areas have). Some areas, mostly seem to be where tides from 2 bodies of water meet (e.g parts of FL, where they get both Gulf and Atlantic tides), have just 1 tide per day. These likely react very differently.

#5

thanks for the info and feedback, on the second trip (SC) I kind of guessed the lag in tidal change would be an hour but actually it was a good bit longer than that. Today the difference at low tide between the harbor and rantowles creek is about 2 hours and 15 minutes according to the tide charts. We put in a couple miles upstream from the intersection with wallace creek so that might add even more additional time. Hadn’t thought about current as an additional variable. I did think about wind.

#6

Tides changes can be pretty amazing if you are in areas of restricted water flow, a narrowing channel in a river or bay, or a very shallow area. I think everybody has seen pictures of the Bay of Fundy where the tide changes and water levels go through great differences. The first time I saw something like this live and in person was swimming in the Sea of Cortez; my son and I had swam out to a little island a few times during the day when we were staying on a beach, We decided to swim out during the dropping tide , and the tide dropped so quickly it was like letting water out of a tub. All of the fish that were in the bay were swimming like mad around us trying to get to open water . Giant fish, rays, sharks swimming past like lightning bolts, unbelievable how many fish were in the little bay with us until they all rushed together to get out.

This summer my family ( wife, sons, son’s girlfriend and a son’s wife and my grandson ) rented an isolated farm house on an isolated fjord in North West Iceland . The high tide line was just about 30 ft from our kitchen window. The tide changes were large, and some of the time we had a rocky kelp garden that stretched for hundreds of yards for a view, and other times a placid dark cold sea lapping at the door step. We started marking time and planning our hikes on the coast by the tides, not the clocks. Except for being in a fjord that was about 5 miles wide there were not a lot of features affecting water flow, but the tide changes did not match predictions from local charts. Very early one morning I couldn’t sleep because of jet lag and walked out on a rocky peninsula in the early daylight and sat down watching the sealife in the tide pools with the sea lapping at the rocks below me, I dozed off for a few minutes to discover my little penninsula was disappearing about as fast as I could scamper over the rocks and sea grass back to firm land. l ended up wading the last hundred yards. The water was cold enough to make me glad I didn’t have to swim for it.

#7

take a look at http://www.deepzoom.com/
it provides tide & current predictions
the current station is not always available - but I noticed they are in the area you are speaking of.
It shows a ‘map’ view of the tides - so you can see the tide/current where you start, move the ‘time’ control and view the tide for where you end up.

where I am (Jax, FL) there is a huge difference between slack current and hi/lo tide.
(downtown, the max ebb lags about 3 hours, iow, max ebb is at about low tide, quite counterintuitive)

#8

Tidal highs and lows and tidal currents have more reliable predictions in places like Cobscook Bay with deep water inputs and outlets. ( Congrats on running the Falls. We did it but only after watching it for a day and correlating eddy lines with high and low tide times from a table…) There always is a lag in current direction change from actual high and low as depending on the mass of water coming in from the new direction tidal current strength direction and magnitude depends on inertia of the water. In Maine the current direction changes usually about an hour after the tide reaches its low and high

Now go to FL and that tide table is at best a hope. Tides can be wildly affected by the wind especially on the shallow drop off areas. Sometimes high tides are lower than lows depending on wind direction fetch and duration… I have been stuck off Lostmans River delta in the mud at… high tide… strong east wind… Not happy.

#9

Trying to guess current flows and coordinating it with tide levels is at best variable. I am extremely familiar with all the factors involved in trying to figure approximately what kind of currents I’ll have to desl with on the Columbia River. Some days and in some places, it’s fairly predictable. Most of the time it is just a guess.

The best you can do is to be ready to go where you want to go, no matter what the tide is doing. If you get a bit of help from the wind, or tide, consider it a bonus. More than half the time, the wind and current will be against you–it’s part of the deal. You learn to read the water and find areas where you can duck out of the stronger flows. More than anything though, it’s having a very fast boat.

#10

I paddled in Alaska for three years. The area has the second biggest tide after Bay of Fundy. I never bothered to track the tides, too much work as you can see from these responses. Pull your boat well above the drift line to camp and enjoy what Nature gives you.