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