Re: current laging tide height, why ?

From: Gr8Jibe@aol.com-DeleteThis
Date: Mon Jul 21 1997 - 21:28:49 PDT


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Date: Tue, 22 Jul 1997 00:28:49 -0400 (EDT)
From: Gr8Jibe@aol.com-DeleteThis
Message-Id: <970722002847_1447876807@emout15.mail.aol.com-DeleteThis>
To: wind_talk@opus.hpl.hp.com-DeleteThis
Subject: Re: current laging tide height, why ?

In a message dated 97-07-21 14:22:38 EDT, you write:

<< the current
> and height of tide are not exactly in sync. Seem to be off by about 1
hour. >>

Knowing this fact is essential to rescuing windsurfers. I spent an hour in
the channel drifting upwind with the ebb current after low tide at 3rd
Avenue, as my rescuers--recognizing that it was low tide--searched for me
where they'd last seen me.

Three factors contribute to our failing to recognize how long the ebb lasts
after low tide at 3rd:

a. Some people don't know there is a difference in timing between low slack
water and low tide.

b. The shallow water on the inside at 3rd Avenue IS essentially slack by low
tide, while the channel current continues to ebb.

c. A windsurfer with board and rig floating on the surface is pushed downwind
by wind and waves, so we will be stationary when the wind and wave action is
balanced by a weak ebb current--which happens to occur around the timing of
low tide at 3rd Avenue.

Therefore, it doesn't matter much whether you use slack water or low tide at
3rd, unless you're searching for someone who is down--and I mean WAY down--in
the water, swimming in the channel or holding a board whose rig is underwater
and acting as a sea anchor.

Your mileage will vary at Crissy, however. Best bet--Carry your phone with
you. (Has anyone tried their PacBell PCS phone in the middle of the bay? Is
there a "dry" sailing discussion group where I could pose this question?)

Bill



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