[Boat] drifting with the current

Luitien Pan luitien at cs.uchicago.edu
Mon Oct 24 02:47:34 CDT 2011


This guy says you *can* steer a boat that's drifting at the same
speed as the current.  If you have a shallow draft and a deep rudder,
then the rudder is reaching down into the slow-moving water at the
bottom of the stream, which lets you steer.

J.R.D. Francis: ``The speed of drifting bodies in a stream''.  Journal
of Fluid Mechanics, vol 1 (1956).
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=367122



Also: a boat can drift faster than the current, if the beam is wide
compared to the depth of the water.

J.R.D. Francis: ``A further note on the speed of floating bodies in a
stream''.  Journal of Fluid Mechanics, vol 10 (1961).
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=365559


I got these references from Jearl Walker's ``The Flying Circus of
Physics'' (John Wiley & Sons, 1997).


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