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 Post subject: Tide schedules
PostPosted: August 4th, 2008, 9:48 pm 
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Location: Ottawa, Ontario, Canada
I just returned from the George River. At the end of the trip we used tide charts available at http://www.mobilegeographics.com:81/calendar/year/2120.html. To our big surprise, these charts were off by about 4 hours. For example, on July 29, the high tide was supposed to happen at 2:44pm EDT, while in fact, the water seemed to be at the highest point at about 6:44pm EDT. I first thought that the difference is due to the error in the time zone, and in fact it is reported in the main Greenwich time, before applying summer time saving, however, at that time it was 10:44pm in the Greenwich.

This makes me very confused. I always thought that the tide schedule was an exact science, related to the position on the Earth and the position of the moon at that time, which is wel calculated and well known.

So, what is this? Just the error on the website? Or tide schedule is as much exact as is the weather forecast? Guys from Newfoundland, who paddled with us, claim that their tidal charts at the Big Rock are precise to the minute.


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PostPosted: August 6th, 2008, 10:24 pm 
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Location: Ottawa
Lester,

Tides are caused by flowing water. To simplify things somewhat, the Sun and Moon cause two 'bulges' of water to travel around the Earth each day, and when this 'bulge' passes any particular place, the general level of the ocean rises (and then falls again). This rising level causes water to flow into inlets, bays, estuaries etc, and out again. This does not happen instantaneously (it takes time for water to flow), so the time of highest water at the mouth of an estuary can be several hours earlier than the time of highest water many kilometres up the estuary. Equally, the time of lowest water at the mouth can be several hours before the lowest water further up (my guess is that the wave of rising water - known as the 'bore' in an estuary - would travel at something like 20 km per hour, depending on the shape of the estuary etc.)

If you were not exactly at the place the tide predictions were made for, then you would not experience the high water at the same time as at that place.

Remember Waskaganish and the tide difference there.

HTH

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PostPosted: August 7th, 2008, 8:57 am 
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We had ther similar problem at Waskaganish on the Broadback trip, but I later realized I used wrong tide station, so this is hard to compare. Tide schedule was perfect in the Leaf Bay last year.

We were checking tides in Kangiqsualujjuaq, looking at their Akalishukalluq Bay. Logically I would assume that the tide predictions are made for Kangiqsualujjuaq. The schedule gave high tide 4 hours earlier, but 10-15 km from Kangiqsualujjuaq there is an open ocean - Ungava Bay.

Before that (being quite ahead of our tripping schedule), we were camping both 14 and 5 km before Kangiqsualujjuaq. The difference (schedule vs. reality) seemed to be approximately the same - about 4 hours.


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PostPosted: August 7th, 2008, 1:16 pm 
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Location: arnprior, Ontario can
Seems the more the effect of river and bays you have, the more out the predictions can be compaired to the nearest station.

WInd and barometric pressure can mess with the tides a little too I belive.


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PostPosted: August 7th, 2008, 8:56 pm 
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Location: Reisterstown, Maryland USA
Yup. What they said.Tide tables are calculated for one point. You have to know your relationship to the point calculated. I guess like decllination with a compass. Around here we get tables for landmarks at varying distances from the main point. The tables say "add+ 25 minutes and subtract 0.4 feet, for example.

Never plan on tide to the minute or to the foot. Wind or location will introduce errors.

Hope this helps

Douglas


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 Post subject: Re: Tide schedules
PostPosted: June 16th, 2016, 9:07 am 
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Joined: January 3rd, 2010, 5:59 pm
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Location: Kanata
Anyone know where to find a tide schedule for Waskaganish?

I can only find one for Moosonee

thanks
rab


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 Post subject: Re: Tide schedules
PostPosted: June 16th, 2016, 10:44 am 
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Location: Rattlesnake Pond ME
Stag Island is close

https://www.fishingreminder.com/CA/char ... d,_Nunavut


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 Post subject: Re: Tide schedules
PostPosted: June 16th, 2016, 12:35 pm 
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Location: Toronto, Ontario Canada
Yeah Stag Island is reasonably accurate (within an hour or so).

Time it right, the last few km can be brutal if you end up with outgoing tide and the current from the Rupert, even worse if you are also fighting against the wind.

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 Post subject: Re: Tide schedules
PostPosted: June 16th, 2016, 1:01 pm 
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Joined: January 3rd, 2010, 5:59 pm
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Location: Kanata
thanks!


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