RE: [Paddlewise] GPS Errors

>From: "Dave Kruger" <kdruger_at_pacifier.com>
> Could be your GPS uses a different datum for its altitude determination
than
> what is used for the tide book's "sea level."
>
> The tide book uses MLLW (= Mean Lower Low Water) as its zero point, while
> USGS topos use a National Geodetic Vertical Datum, usually the 1929 datum,
> which uses MHHW, I think, as "zero altitude."

Makes sense when you stop to think about it. Nautical types divide things
into "Water/Aint water" and land types divide things into "Land/Ain't land"
so that strip of stuff that spends some time as both land and water would be
considered out of play by both groups.

Thanks Dave!

Carey
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