Re: [Paddlewise] Pro's and Con's of the "Swede Form"

Nick, that's the kind of clear explanation I wanted to see.
Thanks
Matt Broze

-----Original Message-----
From: Nick Schade <schade_at_guillemot-kayaks.com>
To: paddlewise_at_lists.intelenet.net <paddlewise_at_lists.intelenet.net>
Date: Friday, May 28, 1999 7:48 AM
Subject: Re: [Paddlewise] Pro's and Con's of the "Swede Form"


>At 9:31 PM -0700 5/27/99, Matt Broze wrote:
><snip>
>>>(SNIP)
>>John said:
>>>Boats do not climb their bow waves nor do they cut through them. Boats
>>>create their bow wave. Regardless of where it lies on the boat the first
>>>wave created (called a pressure disturbance) is the bow wave. I know I
>>>sound like a broken record on this but ................
>>
>>
>>Of course the boat creates the wave but that wave sure looks to me like a
>>hill to climb that is bigger than the hill that would have to be climbed
to
>>reach planing speed if one started from a position where the wave hadn't
>>already been formed. I am well aware that true planing is beyond human
power
>>except with the use of hydrofoils (at least at the present time and into
the
>>forseeable future).
>
>I have used words to the effect of "climbing its own wave" to describe what
>is happening at hull speed myself because, although I knew better, I did
>not understand it well enough to come up with a better explaination. As
>much for my own benefit as anyone elses, I am going to try again.
>
>We tend to think of the waves as creating, or being the source of drag,
>when they are really the visible evidence that drag has already occurred.
>When a hull moving through the water experiences drag, it is due to the
>water applying a force to the boat. This force is sapping energy from the
>boat. For energy to be conserved, the water must increase in energy. In
>other words the water is put into motion by the drag of the boat on the
>water at the same time the boat is being slowed down by the drag of the
>water on the boat.
>
>The energy put into the water by the boat must go somewhere. Some of it is
>lost in frictional heat in turbulence where the water molecules rub against
>each other and heat the water slightly. The rest of it produces waves. If
>there was some other way to disipate the energy the waves would not appear,
>for example if fish were imparted kinetic energy and got squirted out of
>the water, or if little propellors hooked to generators absorbed it all.
>Even if the waves never appear, the drag still would have occurred. Once
>you see the waves it is too late, the damage is done.
>
>When John says "Boats create their bow wave.", it sounds a little obvious.
>We didn't think evil demons were doing making them. But, what it means is
>that the boat can not avoid the wave. If there is a lot of drag the wave
>will be big. If the boat can power its way through the drag and get into
>another drag regime, the wave will change. If the drag diminishes, the wave
>will diminish. You can't climb over the wave because the wave is basically
>innocent. The wave is a side effect, not a cause, of drag.
>
>This is not completely true because the changing wave shape can change the
>flow of water around the boat and this can change the drag, but it is not
>really the wave itself creating the drag. Drag is from friction and
>viscosity.
>
>
>Nick
>
>
>
>
>Nick Schade
>Guillemot Kayaks
>10 Ash Swamp Rd
>Glastonbury, CT 06033
>(860) 659-8847
>
>Schade_at_guillemot-kayaks.com
>http://www.guillemot-kayaks.com/
>
>>>>>"It's not just Art, It's a Craft!"<<<<
>
>
>***************************************************************************
>PaddleWise Paddling Mailing List
>Submissions:     paddlewise_at_lists.intelenet.net
>Subscriptions:   paddlewise-request_at_lists.intelenet.net
>Website:         http://www.gasp-seakayak.net/paddlewise/
>***************************************************************************

***************************************************************************
PaddleWise Paddling Mailing List
Submissions:     paddlewise_at_lists.intelenet.net
Subscriptions:   paddlewise-request_at_lists.intelenet.net
Website:         http://www.gasp-seakayak.net/paddlewise/
***************************************************************************