Wednesday, April 20, 2011

It's all about current...

As the weather starts to get better more people are thinking about getting out on their boat -- one essential part of this is knowing what is going to happen with the tides and currents.  With respect to currents, one of the great resources for predicting currents is the Canadian Current Atlas for Juan de Fuca Strait & Georgia Strait.  This indispensable book is filled with pictures depicting the set and drift of the current as it flows around all the land masses in our area.

One of the problems with this book is that it is keyed off the tides at Point Atkinson (near Vancouver) and in order to use it correctly you have to figure this out, adjust for daylight savings time (if active) and then determine the correct page of the book - all time consuming and prone to errors.

In order to overcome this several enterprising people have pre-computed a set of tables such that all you have to do is lookup the date & time in question and it will give you the page number to look up in the Current Atlas -- how easy is that!  The two most popular tables are Washburn's Tables and Murray's Tables.  Washburn's Tables can be purchased at most marine supply stores in Anacortes, while Murray's tables is a little harder to find being published in Canada.

Of the two, Murray's tables is the preferred one as it handles the exchanges better with the semi-diurnal tides that we experience.

There is however an ALTERNATIVE -- and best yet, it if FREE and available on-line.  You can find them HERE.  Note that there are both HTML and PDF versions, so if needed you can print them up and keep it on the boat for reference.

PS - don't forget the buoy racing season kickoff meeting and barbeque on Wednesday night, April 20 at 6:30pm at the AYC clubhouse.

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