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<DIV><FONT face=Arial size=2>Hi WIlliam, I have a small hand held device
called an Alba Windwatch made by Silva for this job and calculating hydro
heads. The specs claim an accuracy to +- 1.0m. It uses barometric
pressure and so far I have found it pretty good. Only downside is it is
not waterproof so falling in streams can be a problem!</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I always check it out before using it by putting it
on the ground, letting it stabilise and then making sure it registers a change
as I raise it above waist height. One thing to be careful of is the
pressure sensor is mounted behind the battery and the compartment is vented to
allow exposure to the atmosphere so heat from the hand can upset the pressure
reading. It needs to be held by the edges with the fingertips to be
accurate.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Bruce Geddes</FONT></DIV>
<DIV><FONT face=Arial size=2>PowerOn</FONT></DIV>
<DIV><FONT face=Arial size=2>A small place called New Zealand</FONT></DIV>
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size=3><FONT face=Arial size=2></FONT><BR>Accurate enough to size water
pumping systems. I imagine 3 meters total, or +/- 1.5 meters. I
don't need absolute measurements, just relative between two
points.<BR><BR>William<BR></FONT></BLOCKQUOTE></BODY></HTML>