Re: [Paddlewise] GPS

> > ... and the current altitude is normally zero for a kayaker, :-) same
> > as his recent altitude, or am I missing something?
>
> Not if you're in a place with significant tides or if it's your first
> reading on the water since you were on land.
>
> When I first got my GPS back in late '96, I remember getting a couple
> of readings based on only three satellites, but lately I always see
> the better part of a dozen.

Well, tides are quite significant here in BC (I've heard they are 50 years
record, both high and low).  I noticed an errror once, - previously marked
landing spot happend to be covered with water, about 150 ft offshore. But
this was cosistent with tidal activity (I've marked it not at the highest
tide). May be with 3 satellites the location error would be greater, and
would be affected by a few ft altitude change as well, but in last cuple of
years (since I've bought a GPS) I don't remember them being less than 5 or 6
at a time, in this area and on open water.  Honestly, I don't have much use
for it in routine weekend trips, may be I will in a sudden fog or when
forced to paddle in darkness. Btw, GPS uploadable or built-in tidal tables -
they are probably for the USA only, not for Canada or Mexico?
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