Slack Time Predictions: Georgia Straight

[Red Monster]

Just wondering if anyone knows how to figure out the high and low slack times, which are not really the same as high and low tides times. I'm wondering about places around Vancouver and Thrasher. Maybe it's as simple as adding and subtracting from tide times?

 

[Chasin' Dreams]

You'll probably find different answers from different folks. My own findings are slacks are never 100% predictable. You would think they are immediately after ebb and floods but that's just not the case in a lot of areas and even in specific areas they tend to change a bit from how much time after ebb and floods they are. In inlets, areas around lot's of islands, obstructions, eddies etc..the tide flows through this can also affect slack times. The earths rotation and all that other scientific mumbojumbo also has some effect on it too.
Best to check the specific area you are going to be fishing for the tide times then go fish the area, when you think it's supposed to change tides take note on what the water is doing and watch for the slack and make note of it for how long it is after that specific tide. It won't always be the same in that area but it will be close for you to figure out to plan your fishing/trapping trips a bit better.

 

[Fisherman Rob]

Here's a map of tide and current predictions:
http://www.dairiki.org/tides/map.php/disc:d

 

[aheny]

Like the others have said, what you're looking for is slack currents, as opposed to slack tides.
I would check the currents closest to your fishing spot and combine that with your local shack tide, to get an approximation. Then head out to your reef a couple of hours early and just pay attention to when it gets slacker. You might not ever get a zero current, but the time change you notice from the posted current should be more or less consistent.
Also the attached images show the two extreme types of weeks we have, with slack tides being much shorter on the stronger tides obviously.

 

[Red Monster]

I know where to find tide predictions. I'm wondering about how to predict slack (minimum) current? It's easy for somewhere like the Second Narrows: online tables predict times for maximum and minimum currents. Wondering if anyone noticed a way of predicting the slack currents at some of the fishing holes around Vancouver like HITW, Thrasher, QA? Just curious.

 

[Red Monster]

I think people refer to low and high tides as the same time as the low and high slack, and how accurate is that? Maybe I'm over analyzing it?

 

[aheny]

I think people refer to low and high tides as the same time as the low and high slack, and how accurate is that? Maybe I'm over analyzing it?

Maybe you're underanalyzing it? Typically what you're trying to do is find the current for an area that doesn't have reported current for it. You need to average it out, estimate and then go out and find the actual conditions.
For example at the hump, you have the local tide, then you have a prevailing current, then there is flow out of Howe sound and Indian Arm. Then there is the pressure of the wind moving water in and out of each area.
Personally I just keep notes on local conditions and slowly get a better understanding of what each area is like.
Some people get frustrated and just say that you can't predict the conditions of some areas, but I just think they're not taking into consideration enough variables.

 

[ryanb]

Every location has its own unique patterns. Some you can figure out based on tides and nearby current stations, others the only way to figure it out is to get out there and see what happens on any given tide. For the Fraser mouth, sand heads to North arm I find on an average tide slack current to be around +3hrs from slack tide. The size of the tides change the calculation.

 

[Goathorns]

The QA should be very close to the Point Atkinson tide tables. However Thrasher and Porlier have the passage between the islands to deal with. On the big tides the current starts up through the pass about 4 hours ahead of time. If you go to Porlier to jig cod in the pass, you can't use the point atkinson tide table, you will be about 4 hours to late! I think aheny is correct in the averaging it out idea and also the prevailing current idea. There seems to be a current to the SW when I troll towards the Hump from Cowans point, and an north east/flood current at thrasher most of the time. I don't seem to find a current going south on the ebb unless I'm along the bell buoy, or Sturgeon Bank off the vancouver water front. The idea of finding a slacker piece of water at thrasher is interesting, even if u have to boat around a bunch and find it. Some people will stop at thrasher and drift just to see how fast the current is. This is one of the reasons to buy the green book, canadian hydrographic tables for tides and currents.

 

[Red Monster]

Hmmmm... good information, guys. The currents at Thrasher always seem to be intense. I think I need an app to figure this it out.
I can figure the 3 hour delay idea for between the Fraser Arms using Point Atkinson tides I assume. Good to know.
QA is about the same as PA. Good to know.
Thrasher is...? There's a Gabriola tide table that might help to predict slack current?

 

[agentaqua]

These links may be of some assistance:
http://www.charts.gc.ca/publications/atlas-eng.asp
http://www.tides.gc.ca/eng/data/currents/2017
https://www.starpath.com/catalog/books/1806.htm
https://www.starpath.com/catalog/books/pics/208.jpg
http://andrewswims.com/projects-2/sjdf/
http://www.canadianyachting.ca/dest...idal-passes-part-1-passes-of-the-gulf-islands

 

[Fisherman Rob]

You can purchase Murray's Tables. It has highly detailed information on currents for specific locations. Basically they overlay an arrow, the size representing the magnitude of flow for every hour of the day on charts all along the coast.

https://www.nauticalmind.com/81435/murrays-tables/

Here's a sample chart:
https://bcwavewatcher.files.wordpress.com/2013/11/p1230292.jpg

 

[aheny]

Hmmmm... good information, guys. The currents at Thrasher always seem to be intense. I think I need an app to figure this it out.
I can figure the 3 hour delay idea for between the Fraser Arms using Point Atkinson tides I assume. Good to know.
QA is about the same as PA. Good to know.
Thrasher is...? There's a Gabriola tide table that might help to predict slack current?

There is actually a Gabriola pass current table as well, which also helps.
I would start by going on a day where you have a long flat triple tide like in the attached image, with half a day off not a lot of water moving you can get slack water over a reef, as long as there isn't a wind applying pressure to it.
The issue with a day like that is you don't have a short slack tide or a hard ebb to focus the attention of the fish.

 

[bigbruce]

Some chartplotters (e.g. Garmin g2 vision bluechart) have tide and current tables for various points along the coast.

 

[Sotally Tober]

Here is a current table for Gabriela Pass on the dairiki.org website.
I think someone has posted the link already.