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» Online Classroom   » Inland and Coastal Navigation   » Public Discussion of Inland and Coastal Navigation   » Current Atlas for Johnstone Strait to Prince Rupert

Author Topic: Current Atlas for Johnstone Strait to Prince Rupert

 - posted March 22, 2019 04:22 PM      Profile for Satchel           Edit/Delete Post 
I haven't been able to find a current atlas for the waters between Johnstone and Prince Rupert/US border. Does anyone know of a reference for this area?

From: Alameda, CA
David Burch

 - posted March 22, 2019 04:58 PM      Profile for David Burch           Edit/Delete Post 
We have very good Atlas north of there on to Ketchikan in our SE Alaska Current Atlas, which is much better than the official tables, and we have resources for the inside of Vancouver Is south of there in a GPX set of current stations. But where you ask about, you are pretty much on your own.... but you can do very well with some resources to help.

namely some CND charts show current arrows (at peak flow) , recalling the flood has feathers, see ie chart 374. But maybe better still you can use OpenCPN (mac or PC) to view all tide and current stations in that region. then click each to see hourly data.

then you have to piece together the flow pattern between these stations based on the tides and currents showing and your own readings.

the Canadian Sailing Directions also have many notes on currents in this region.

Sophisticated programs like Expedition can pull out the actual current you experience based on measured BSP, SOG, Heading and COG. but instruments must be calibrated.

then knowing your actual current compared to estimated flow you have something to go by for planning ahead.

note too that the free program opencpn has a tactics plugin that will also extract current from the sensors mentioned.

In the image below, green icons are tide stations; orange are current stations.

From: Starpath, Seattle, WA

 - posted March 25, 2019 02:25 PM      Profile for Satchel           Edit/Delete Post 
Thanks David! We have the SE Alaska Current atlas, and the Van/Strait references. I will check out the Canadian sailing directions!
From: Alameda, CA

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