Re: HydroDynamic Lifting

[EMAIL PROTECTED] (marco) wrote in message news:<[EMAIL PROTECTED]>...
> I have been discussing hydrodynamic lifting (HDL) with a lot of people
> in the past few years.  I have been asked from some of the Italian
> coaches to write an article about it.  So I was wondering if I can ask
> for your help to make sure I do not say anything stupid about it.  The
> general tendency of many of the Italian coaches is that there is no
> such a thing as HDL.  I discussed it with Giuseppe Di Capua  and
> Giovanni Postiglione and both strongly believe that there is no
> evidence to support the "theory" behind HDL.  My personal opinion is
> that if it is true that we don't have enough evidence (for what I know
> and please help me here if you are better informed than I am) it is
> also true that without the HDL you can not explain any kind of
> technique that suggests a 70% catch angle 30% finish angle because
> from the physics point of view it doesn't make sense at all.
> Gianni (Postiglione) made the hypothesis that this kind of 70/30
> partition of the stroke will allow a narrower angle of approach of the
> blade to the water avoiding to slow down the boat during the catch,
> but I still believe that is not enough to justify the really
> disadvantageous angle that we will have at that point to apply
> pressure.
> Beppe (Di Capua) told me that he talked about it with a famous boat
> designer (involved with the design of Alinghi unfortunately I can't
> recall his name) who said in his opinion the velocity of the parts
> involved (water/blade) is not sufficient to justify any form of
> lifting, but he wasn't able to give me an explanation to give me an
> alternative explanation.  I found it very interesting, that Italian
> coaches who are probably some of the biggest "fans" of this kind of
> set up (70/30) are also the ones that believe less in HDL.  I know
> that I will not be able to bring an end to this discussion, but I
> would like once again to have the opinion of both sides regarding HDL.
>  Please if you answer to this thread let me know if you would like to
> be quoted or not and give me your name and title so I can give you the
> rightful credit.
> Ciao
> Marco

Marco:
  For a comprehensive presentation on oarblade lift and drag see:
<http://www.atkinsopht.com/row/liftdrag.htm>.
  For some discussion on catch angles greater than 70 degrees (bow
angle less than 30 degrees) see
<http://www.atkinsopht.com/row/bowangle.htm>.  Small catch bow angles
may be advantageous.
  Also for some discussion on blade cant angle (possibly important for
sweeps) see: <http://www.atkinsopht.com/row/bladangl.htm>.
  Good luck and best regards,
Bill