Re: Tide at 3rd

From: Ken Poulton (poulton@zonker.hpl.hp.com-DeleteThis)
Date: Fri Sep 18 1998 - 09:20:30 PDT

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Date: Fri, 18 Sep 1998 09:20:30 -0700 (PDT)
From: Ken Poulton <poulton@zonker.hpl.hp.com-DeleteThis>
Message-Id: <199809181620.JAA26229@zonker.hpl.hp.com-DeleteThis>
To: wind_talk@opus.hpl.hp.com-DeleteThis
Subject: Re:  Tide at 3rd
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> COTW reports a low tide of 1.58 feet at 5.48pm today at Coyote. Can somebody
> please tell me how this relates to safe sailing times at 3rd. I seem to
> remember that level is getting pretty marginal, isn't it?

It's getting to where the bars start being a hazard.

>From my FAQ windspeed.info:

=== Tides and Hazards ===
These discussions use location-adjusted tide values.

The program also calculates "safe" times for 3rd and Palo Alto. These
are chosen at pretty conservative levels: +2.5 for 3rd and +4.0 for Palo
Alto. At these heights, I sail with no worries. At both sites I sail
in as much as a foot less after reminding myself where the bars are.
(One foot typically corresponds to 40-60 minutes time difference.)

    Disclaimers: The calculated tide levels may be wrong, or the
    measured "safe" levels may be wrong. Sandbars shift, people leave
    anchors or other trash in shallow water. You might be sailing with
    a fin deeper than mine. A near-miss by an asteroid might produce an
    extra low tide. Lawyers may be lurking just below the water surface
    at any time, any place. Shit happens. So use your own judgement at
    all times and don't blame me if you hit something.

For 3rd Ave, +3 feet is the safe limit for the old launch by the blue tanks
(using the SM-adjusted tides, a little over +2 feet for GG height). At
the new launch (fenced lot) +2.5 feet is fine. +2.0 feet is still okay
for launching but is beginning to make hazards of the 4 sandbars between
the launch and the channel. The bars are:
    1) along the edge of the channel, from the channel marker towards the
        bridge - 0 ft near the marker, +1.5 ft near the bridge;
    2) about halfway from the old launch to the channel marker - +1 ft;
    3) two bars within 400 yards of the new launch, maybe 0 feet. These
        each stretch upwind starting approximately on a line between the
        new launch and the channel marker.

For Coyote Point, 0 feet is fine (you have to walk out 100 yards, but
the mud is less than 6 inches deep). There was a recent report of a
sandbar at about -1 feet just outside the swim area, however. There is
also now a post broken off at about +1 ft, situated halfway between the
two remaining posts on the side of the swimming area next to the launch
beach. Another sailor reported a 1" pipe at a 45 degree angle, top at
about +2.5 ft, about 3/4 of the way along the swim area and maybe 50 yards
upwind from the poles (just downwind of a beam reach from the upwind
corner of the swim area).

At Crown Sterling, 1 foot is enough to launch, but you need 2.5 feet to
be clear of the sandbars. The main one lies across a line between the
Crown Sterling launch and the pole in the water just south of the runway
piers (this line is nearly directly across the usual wind). It sits
about two thirds of the way from the shore to the pole, running roughly
parallel to the wind direction, maybe half a mile long. The upwind end
is at 0.0 feet, the downwind end is at +0.4 feet. There is another at
around -0.5 ft around 100 feet upwind of the pole and another downwind
of the pole (may be continuous). There is some other kind of
obstruction at -1 to 0 ft further out along the same line. Near the
shore, there is a pole with its top at +1.0 ft; it is 125 yards north of
the hotel and 30 yards from the shore.

Ken Poulton
poulton@opus.hpl.hp.com-DeleteThis

"If you've seen one redwood tree, you've seen them all."
-- Forestry expert Ronald Reagan

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