[Public-list] Photos of Boom vang?

Don Campbell dk.campbell at sympatico.ca
Wed Sep 21 07:30:23 PDT 2005


When it comes to measurements of vang placement, it might help to work out the
moments of force for the different positions possible and this is done by
multiplying the force applied by the distance to the fulcrum or pulling point
resolved trigonometrically for the angle of pull.  With a 4:1 mechanical
advantage, this amounts to about 350 lbs for the resultant force on the vang,
since the normal pull for a man is 75 lbs. Thus every foot further aft for the
location of the  boom bail adds some additional force downward on the boom.
This needs to be balanced by the capabilities of the boon to withstand the
force and the size of bail (and bolt)  needed. We are fortunate that the
mainsheet is end boom sheeting, because it too adds downward force, where a
mid boom sheeting will allow the boom to bend up due to sail leech forces.
Don
#528

Brian Palmer wrote:

> Thanks for posting these George!
>
> -Brian
>
> On 9/20/05, George Dinwiddie <gdinwiddie at alberg30.org> wrote:
> > FINNUS505 at aol.com wrote:
> > > How far aft on the boom is that bail, George?
> >
> > I haven't measured.  It looks like it's a little further than the height
> > of the boom.  The pictures are at
> > http://www.alberg30.org/maintenance/disorganized/vang/
> >
> >
> > --
> >   ----------------------------------------------------------------------
> >    When I remember bygone days                         George Dinwiddie
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> >    So many I love were not yet born.
> >                                              'The Middle' by Ogden Nash
> >   ----------------------------------------------------------------------
> >
> >
> >
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