NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: 'pacing' for boat speed
From: Jeremy C
Date: 2011 Apr 14, 10:08 -0400
From: Jeremy C
Date: 2011 Apr 14, 10:08 -0400
This technique is known to me. The old timers tell me that if the
Doppler log died and they had no traditional log, jetsam was released on the bow
or bridge and the elapsed time to the stern was used to calculate the speed
through the water.
Given a ship is 400-600 foot long, you can be fairly confident with
your speed determination can be decent with a stopwatch.
When your are talking about a 30-60 foot yacht, the speed accuracy
diminished due to the lack of time precision.
Now of course we have GPS speeds as well as the log, so if the log is dead,
you just go with GPS. Frankly, the speed log on my ship has either not
worked, or been wildly inaccurate for years.
JCA
In a message dated 4/13/2011 6:43:41 P.M. Eastern Daylight Time,
apacherunner@gmail.com writes:
Here's a question about the historical practice of reckoning a boat's speed on the water. The use of log-lines is pretty much a given.In historical accounts, of varying accuracy, I've read about one technique called 'pacing', where the mariner drops some garbage in at the hull and walks toward the stern, keeping abreast of the garbage. I've also read an assertion by Samuel Eliot Morrison that Magellan's captain has a quote that corresponds to finding boat speed by counting the time it takes a piece of flotsam to move along the hull.I've also heard that it's more of an intuitive feel.I'm a sea kayaker and not a sailor, so I estimate the speed from my paddling and the wind conditions - I'd probably vote for the more intuitive school if you were to ask me, but I'm curious whether anyone in the past practiced some technique using the timing of flotsam passing by.
