judging current; rules of thumb?
Jeff wrote:
jlrogers±³© wrote:
"Jeff" wrote in message
. ..
Shaun Van Poecke wrote:
Here's one for those of you out there without onboard
instruments/knotmeter/gps....
Is there any reasonably accurate (say, within a know or so) way of
judging the current, when you are under way, and there are no fixed
objects within sight?
Shaun
No, there aren't.
--
jeff
Yes, there is.
OK, please explain. Maybe this will bring Jax out of the woodwork to
tell us that Einstein proved that dead reckoning is impossible.
Use a venturi/pitot boat knotometer and rotate it 360 degrees noting the
speed accurately for increments of angle.
If it reads 0 knots for all angles your GPS speed is the current speed.
If it reads 5 knots forward, 0 knots aft and the GPS speed is 4 knots
the current is 1 knot from aft.
The same procedure is done for sideways currents but one must use
trigonometry, a feat easily accomplished on my Mensa circular mind meld
slide rule. I can do all the calculations in my head while wearing just
a set of Speedo briefs.
I've devised a set of Lorentz contraction gauges to measure all absolute
motion precisely in 3 dimensions. Aliens are after me to keep this gift
to mankind from falling in human hands so I must travel in disguise.
Jax
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