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From: Evan Dallas <Evan_Dallas_at_notes.ntrs.com>
subject: [Paddlewise] Tidal flow for west coast of Canada
Date: Wed, 2 May 2001 11:11:26 -0700
I've heard from one paddler that in addition to the local tidal currents that
flow into and out of the various bays and inlets on the west coast of Canada
(I'm mainly interested in Vancouver island), there is also a general tidal flow
that runs north and south along the entire coastline.  Given the "diagonal"
alignment of Vanc isl (i.e. running from a southeast to northwest orientation),
I'm guessing that the large tidal swell off the coast probably pushes water more
or less due east, which would then be diverted along the coast towards the
southwest (due to the diagonal alignment); with the opposite happening as the
tides pull back -- but that's purely my own speculation.  In actual experience,
I haven't noticed much of an effect.  Does anyone have more definitive
information (or links) that would explain this further?

Evan Dallas
Woodinville, WA



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From: Dave Kruger <dkruger_at_pacifier.com>
subject: Re: [Paddlewise] Tidal flow for west coast of Canada
Date: Wed, 02 May 2001 19:23:56 -0700
Evan Dallas wrote:
> 
> I've heard from one paddler that in addition to the local tidal currents that
> flow into and out of the various bays and inlets on the west coast of Canada
> (I'm mainly interested in Vancouver island), there is also a general tidal flow
> that runs north and south along the entire coastline.  Given the "diagonal"
> alignment of Vanc isl (i.e. running from a southeast to northwest orientation),
> I'm guessing that the large tidal swell off the coast probably pushes water more
> or less due east, which would then be diverted along the coast towards the
> southwest (due to the diagonal alignment); with the opposite happening as the
> tides pull back -- but that's purely my own speculation.  In actual experience,
> I haven't noticed much of an effect.  Does anyone have more definitive
> information (or links) that would explain this further?

The tide wave moves SW to NE (and the reverse) on the OUTSIDE of Vancouver
Island.  What happens inside VI is a mess, because the tide "arrives" at the N
end of VI from the "outside" out of phase from its arrival from the "inside" of
VI.

It ain't simple.  Best to use tide/current info specific to the location of
interest.

-- 
Dave Kruger
Astoria, OR

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From: Mary Z <mzuschlag_at_home.com>
subject: RE: [Paddlewise] Tidal flow for west coast of Canada
Date: Wed, 2 May 2001 21:21:20 -0700
Dave is correct. It is primarily the northeast side of Vancouver island is
affected by the North to South flood tide.  In Johnstone Strait it floods
north to south.  When you get in the southern Discovery Islands, and in
Sutil Channel in particular, the tide is flooding from the "usual direction"
south to north.  However, in the neighboring Discovery Channel it floods
from North to South.  Up one channel and down in the other.  Go figure!
Makes for some extremely interesting currents.  Things are out of phase, and
those narrow passages mess everything up. -- MZ

website:
http://members.home.net/mzuschlag


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From: Al Gunther <agunther_at_silverlink.net>
subject: Re: [Paddlewise] Tidal flow for west coast of Canada
Date: Thu, 3 May 2001 08:17:55 -0700
Evan Dallas wrote:

>I've heard from one paddler that in addition to the local tidal
>currents that flow into and out of the various bays and inlets on the
>west coast of Canada (I'm mainly interested in Vancouver island),
>there is also a general tidal flow that runs north and south along the
>entire coastline.  Given the "diagonal" alignment of Vanc isl (i.e.
>running from a southeast to northwest orientation), I'm guessing that
>the large tidal swell off the coast probably pushes water more or less
>due east, which would then be diverted along the coast towards the
>southwest (due to the diagonal alignment); with the opposite happening
>as the tides pull back -- but that's purely my own speculation.  In
>actual experience, I haven't noticed much of an effect.  Does anyone
>have more definitive information (or links) that would explain this
>further?

The only "general tidal flow" is from the ocean inland. This is what
generates the currents where geography restricts the flow. (For those
unfamiliar with the area, the currents reverse 4 times every 23 hours with
tide differentials of up to 16 feet.) There is an ocean current, however,
that flows up the coast, NW to SE in the summer, reversing in the winter.
Perhaps this is what you have reference to. I soloed around Vancouver
Island a few years ago in a small sailboat in June. I traveled most of the
outer coast with other sailboats and we always took different paths from
bay to bay. I always opted for the close to shore route, anchoring and
going to shore where I could, whereas the other boats went several miles
out. I found reverse, eddy currents within a mile to half mile of the
shore, sometimes as much as three knots, where by tacking out a mile, I
could gain the favorable current that the other boats were having. By
comparing GPS speed to my knotmeter, it was a real education in how these
currents travel. Off Estevan Point, for example, I was caught in a 3 knot
current that ran due west. June is a transition month so I'm not sure what
one might expect at other times of the year, and in the Pacific in recent
years, no two years have been the same.

One thing is for sure, many of those inlets run many miles deep and with a
spring ebb tide and any ocean swell, the water can stack up very steep at
their entrances.

Al Gunther, Kingston, WA  <---- 47° 48.1'N, 122° 30.0'W




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From: Jack Fu <SeaDogJack_at_cablespeed.com>
subject: Re: [Paddlewise] Tidal flow for west coast of Canada
Date: Thu, 3 May 2001 10:03:57 -0700
I don't know if this information applies to this thread,
but try looking in "Current Atlas - Juan de Fuca Strait to Strait of
Georgia"
published by the Canadian Hydrographic Service. Use it with
"Washburne's Tables 2001".

The Current Atlas is available at most outfitters and costs about $28. It is
good forever. Washburne's Tables comes out annually and costs about $6.

This combination has been very useful to me in planning trips in the
San Juans and the Gulf Islands. It's figured out the currents for you
for every hour of every day of the year, so you don't have to pore
over the tides tables etc. yourself. It's like cheating!

In New England there is a similarly helpful publication called
(I think) "Eldridge's Tables."




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From: Giuseppe <Giuseppe.Cabras_at_fisica.uniud.it>
subject: Re: [Paddlewise] Tidal flow for west coast of Canada
Date: Thu, 03 May 2001 13:52:54 +0200
Dave Kruger wrote:
> 
> Evan Dallas wrote:
> >
> > I've heard from one paddler that in addition to the local tidal currents that
> > flow into and out of the various bays and inlets on the west coast of Canada
> > (I'm mainly interested in Vancouver island), there is also a general tidal flow
> > that runs north and south along the entire coastline.  Given the "diagonal"
> > alignment of Vanc isl (i.e. running from a southeast to northwest orientation),
> > I'm guessing that the large tidal swell off the coast probably pushes water more
> > or less due east, which would then be diverted along the coast towards the
> > southwest (due to the diagonal alignment); with the opposite happening as the
> > tides pull back -- but that's purely my own speculation.  In actual experience,
> > I haven't noticed much of an effect.  Does anyone have more definitive
> > information (or links) that would explain this further?
> 
> The tide wave moves SW to NE (and the reverse) on the OUTSIDE of Vancouver
> Island.  What happens inside VI is a mess, because the tide "arrives" at the N
> end of VI from the "outside" out of phase from its arrival from the "inside" of
> VI.
> 
> It ain't simple.  Best to use tide/current info specific to the location of
> interest.
> 

Did you try a look at
http://www.fisica.uniud.it:8080/zones/:America/Vancouver for tide and
current prediction? May be useful.

Cheers,
                                         Giuseppe

Phone: +39-043255-8212  University of Udine - Department of Physics
Fax:   +39-043255-8222     via delle Scienze, 208 - 33100 UDINE
                          URL:http://www.fisica.uniud.it/~cabras

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