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I suppose it is a personal matter: I feel more happy with a little bit (
more) weight and as a result of that more inertia.
Less weight can also be a selling argument for instrumentmakers.
Regarding your "skeleton"argument: if you make a disc like sextant it will
be very prone to windinfluence
A little bit out of the "navigation lane" : with bicycles in a race ( time
trials) there is also the argument of using "open"wheels or "disc"wheels
because with the wind in the wrong direction the disc wheels have a negative
influence.
I am Dutch that's why I bring up the bicycle!

I short to me: skeleton frame with a certain weight is perfect!

Willem Piccer

----- Original Message -----
From: "george huxtable" 
To: 
Sent: Wednesday, September 28, 2005 1:05 AM
Subject: Re: beginner


> At 10:56 19/09/2005, Willem Piccer wrote, about the weight of an observing
> instrument-:
>
> >Weight is something which plays a minor role in the discussions we see
here
> >about the plastic sextant but to me it is important.
> >
> >If you use your sextant on a platform which is not stable than a sextant
> >which has a certain weight will help you to obtain a more accurate
> >observation because it is more stable.
> >I know there is a sextant from John Bird ( around 1770) which has a
"stick"
> >on the backside to make it more stable.
> >
> >I suppose there is an optimum weight for a sextant : on one side not too
> >heavy to handle and on the other side heavy enough to obtain a good
> >observation.
> >I remember when we started to use these light East German sextants that
this
> >was exactly  what was noticed: easy to lift but more difficult to make a
> >good observation
>
> =======================
>
> I've seen that sentiment expressed before, by other seasoned professional
> mariuners, and I would like to understand the basis for it. Why should a
> heavy sextant be more stable, I ask (as someone who only ever owned a
> plastic sextant, but has used others)? I respect the views of those who
> have much more experience than I do, but remain as yet unconvinced.
>
> After all, the windage on a sextant is just the same, when made of a light
> material or a heavy one, if they are the same shape and size. If a sextant
> is physically smaller, as some yachtsman's models are,  then wind forces
> will be less. True, a heavy sextant will have more inertia, so it resists
> initial movement, but when moving with the ship's roll, then it acquires
> extra momentum, which makes it harder to bring it to a stop.
>
> Sextant makers all seem to go to a lot of trouble to skeletonize the
frames
> of their instruments. If there was as advantage in having a heavier
> instrument, why would they bother to do so?
>
> The clinching argument, to my mind, against Willem's view, is that if
> weight was a real advantage, mariners would "improve" their lightweight
> instruments by simply adding lead ballast, to make the thing more
"stable".
> I have never heard of this being done, to any sextant, though it would be
> easy to do in practice. Why not, then, if the extra weight would make it
> somehow better? Convince me that it would.
>
> =======================
>
> I've missed recent Nav-L discussions, having been away on a family holiday
> (four aboard) on a hired motor-cruiser on the River Charente, in
south-west
> France. For me, a real change, in that the only navigational decision was
> whether to set off upstream and return downstream, or vice versa. It made
> for a good holiday, but reinforced my preference for salt water, and
sails.
>
> George.
> ===============================================================
> Contact George at george@huxtable.u-net.com ,or by phone +44 1865 820222,
> or from within UK 01865 820222.
> Or by post- George Huxtable, 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13
> 5HX, UK.
>

   

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