Re: [Paddlewise] Back to basics

From: John Winters <735769_at_ican.net>
Date: Thu, 12 Mar 1998 07:42:38 -0500
Ari wrote:

(SNIP about conversion - units rather than religous))

Here in Canada we are expected to be fluent in two languages (never know
that from my French) as well as two measurement systems plus must be able
to spell in two versions of English (Americans don't use enough "u's").
Worst of all, we have to understand two interrogative grunts ("Eh" and
"Huh").  Any wonder we are so screwed up. By the time we figure out what is
going on it is too late.

Some one will surely have supplied the proper conversion factors but most
of the me one doesn't much care about precision so here is my quick and
dirty method.

Multiply 1 knot by 0.6 to get feet/second, 0.5 to get kilometres/ hour, 2.0
to get meters/sec, and 0.9 to get miles/hour.

These units become a big problem occasionally. We hear a lot about the hull
speed and that it is 1.34 *LWL^.5 but this is only true if the units are
feet and knots. It is 1.55 * LWL^.5 if you use feet and Miles per hour and
1.25*LWL^.5 in metric units and 2.4*LWL^.5 if you use knots and meters.

This is why I prefer the Froude number which is constant for any
consistent set of units. The Froude number is V=(g*LWL)^.5 where g is the
acceleration due to gravity. So long a one knows that the typical paddling
speed range is  between Fn 0.23 and Fn 0.30 and that racing paddlers peak
out at 0.60 it is easy to handle.

Cheers,
John Winters
Redwing Designs
Specialists in Human Powered Watercraft
http://home.ican.net/~735769/




***************************************************************************
PaddleWise Paddling Mailing List
Submissions:     paddlewise_at_lists.intelenet.net
Subscriptions:   paddlewise-request_at_lists.intelenet.net
Website:         http://www.gasp-seakayak.net/paddlewise/
***************************************************************************
Received on Thu Mar 12 1998 - 05:20:44 PST

This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:29:54 PDT