Re: [Paddlewise] Planing

On Thu, 17 Jan 2002 09:36:53 -0500
  "John Winters" <jwinters_at_onlink.net> wrote:
>
>These things always cause problems.  However, Dr. 
>Savitsky pointed out that
>the rise in CG during surfing could occur but you could 
>not call it planing
>any more than you could say a person falling off a 
>building was flying
>because he generated some lift. The distinction between 
>planing and not
>planing is the vertical rise caused by the boat's power 
>not an outside
>source.

You seem to imply that nothing can "fly" without an 
internal power source.  I disagree with that; sailplanes, 
hang gliders, and even balloons do fly, despite having no 
internal power source. 

Despite a "flying suit" on a skydiver I once saw, I would 
say that flying requires that most of the weight of the 
object to be supported by the air - either by buoyancy or 
lift (and not by drag, so we can rule out terminal 
velocity falls).  I would not require that all the weight 
be supported by buoyancy or lift, as there is some drag 
weight support for any flying object in a descent, but 
certainly the vast majority of it. 

Continuing this analogy to planing suggests that we need 
only require that the great majority of the boat's weight 
be supported by hydrodynamic forces on the hull and not by 
static displacement, and need not depend on internal power 
sources.  

Agreed, some measurable rise in CG doesn't get us there, 
any more than some measurable lift converts falling to 
flying, but if not planing, what do you call it?  

And how does it differ for a sailboarder, who also has no 
internal power source?  I have often heard that described 
as planing.

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