Re: Re: Discrepancy between COTW Coyote tides and Ken's SM tides

From: Kirk Lindstrom (kirk@hpmsd3.sj.hp.com-DeleteThis)
Date: Fri Aug 25 1995 - 07:20:25 PDT


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Date: Fri, 25 Aug 1995 07:20:25 -0700
From: Kirk Lindstrom <kirk@hpmsd3.sj.hp.com-DeleteThis>
Message-Id: <199508251420.AA016140425@hpmsd3.sj.hp.com-DeleteThis>
To: James.Paugh@Eng.Sun.COM-DeleteThis
Subject: Re: Re: Discrepancy between COTW Coyote tides and Ken's SM tides
Cc: wind_talk@opus.hpl.hp.com-DeleteThis


> What I would like to hear is an explanation of why slack current occurs after
> say, a low tide. For instance, today, low tide at Crissy is at 5:03pm, but
> low slack is at 7:29pm! How is it that slack current occurs 2.5 hours after
> low tide?
>
> ~Jim
>
It has to do with the shape of the bay. If you are an EE, then you can
model the bay as a bunch of capacitors in each big, deep section and
each "straight" as an inductor with the largest inductor at the Golden
Gate. The "system" is driven by tide height (Voltage input) at the
Golden Gate. Voltage is the same as tide height and current is the same for
both with one being water and the other electrons.

Another REALLY simple model is a rock on a spring. Push the spring and
the rock moves in the direction of the push (Water moving in reaction to
tide height rising at the gate). Stop puching on the spring and the
rock will still move away from you for a bit before it is pulled back by the
spring. The current in the bay is doing a similar thing with the push
from the tide height at the Gate.

Kirk out
 



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