On Wed, 21 Jan 2004 18:54:21 +0000, Harry Krause wrote:

Lloyd Sumpter wrote:

Hi,

I still have the thru-hull from a long-dead knotmeter in Far Cove. I
may be able to dig up the partially-working paddle-wheel sender (iirc needs a
new paddlewheel).

Can I get a new sender, with proper documentation so I know how it
works, and hook it into my laptop? The Signet sender appears to put out a
voltage more-or-less proportional to speed, correct? So I would need a bit of
electronics (buffer/amp? and A/D) to put the value into the parallel port of
the laptop. Then a few runs with a GPS in still water should allow me to
calibrate it.

Where can I get data on what these senders actually put out?

Lloyd Sumpter
"Far Cove" Catalina 36 - waiting for new engine


Sheesh, Lloyd, why don't you plumb that through-hull and add something useful,
like a baitwell?

Knotmeter...whyfor? You have a main GPS working of your mains, and a backup GPS
that works off its own little batteries, right?

Just interface one of the GPS units with your laptop.

Already done that with the backup GPS.

You wouldn't know this sitting in your armchair, but in the Actual Ocean, there
are currents, waves, etc. which make the "speed over ground" calculated by the
GPS not the same as "speed through the water", which is what a knotmeter shows.
Now, for 50 points and what's behind Door #2: When testing a new engine for
performance, which speed value should you use? (cue Annoying Jeopardy Waiting
Music...)

Lloyd Sumpter
"Far Cove" Catalina 36