G'day,
The reason the booms are wood cored, yet masts are solid carbon is that the
beams have to be stiffer (deflect less), therefore they are a bigger
section. The wall thickness required solely for strength is not sufficient
to resist buckling, whereas on the mast, it is.


regards,

Rob
----- Original Message -----
From: "Robert" <cateran1949@...>
To: <harryproa@...>
Sent: Monday, January 19, 2004 9:41 AM
Subject: [harryproa] Re: Beams to windward hull


> -Todd,
>
> I went over the building of Harrigami and the pictures show the
> methods. The actual dimensions are another matter.
> The cost of carbon tow is starting to come close to that of wood.
> marine ply at about $6 per kilo, bendy ply $12-15 and quality cedar
> >$20. I would be curious about the cost and weight of a mast made
> from carbon tow over timber compared with all carbon. Rob reckons it
> comes down to going all carbon with their technique of strip planking
> with pressure bonded carbon tow strips.
> I suppose, once you are set up to handle carbon tow reinforcing with
> vacuum bagging and wetting out, you might as well go the whole hog
> for a mast and go all carbon and keep the weight down.
> The beams of the latest Visionary built by Mark at Gosford is a
> lovely example of a bamboo structure built with modern materials,
> with a skin strong and stiff in tension, a wood underneath thick
> enough to resist buckling under compression and bulkheads, to further
> resist buckling. I am not sure why the numbers should work for making
> the mast all carbon and the beams a combination of wood and carbon.
> Robert
>
>
> robert.
> -- In harryproa@..., "Todd" <ktsrfer@m...> wrote:
> > Where can you find more information on building carbon mast and
> > beams?
> >
> > Todd
> >
> >
> > --- In harryproa@..., "rob denney" <proa@t...> wrote:
> > > G'day,
> > >
> > > There are a few variables, but basically, 400 gsm uni glass is
> > about $15 per
> > > kg, 300 gsm carbon uni is about $150/kgand carbon tow is $30/kg,
> > epoxy is
> > > about $13 per kg. Depends how much you buy and where, but these
> > are ball
> > > park for bulk in Aus. The carbon will be 6 times stiffer than
> the
> > glass,
> > > and near enough 150% as strong.
> > >
> > > Regards,
> > >
> > > Rob
> > > ----- Original Message -----
> > > From: "Robert" <cateran1949@y...>
> > > To: <harryproa@...>
> > > Sent: Wednesday, January 14, 2004 12:23 PM
> > > Subject: [harryproa] Re: Beams to windward hull
> > >
> > >
> > > > -What is the price differential of carbon against glass,
> > especially
> > > > by the time you add the extra resin needed for the glass?
> > > > Robert
> > > >
> > > > -- In harryproa@..., "Tony Richardson"
> > > > <atrichardson@b...> wrote:
> > > > > As it is such a small boat I would suggest putting on what you
> > > > think will do and have a go.
> > > > > Ply box section beams are strong, light and easy to build.
> > > > > If you were a bit clever with glass you could overlay glass
> > uni's
> > > > onto PVC drainpipe. Wrap the unis in mat and there is your beam.
> > > > Leave the PVC inside.
> > > > > No Rot problems
> > > > > How much glass and where etc? Experiment/Guess
> > > > > Rgs
> > > > > Tony
> > > > > ----- Original Message -----
> > > > > From: Todd
> > > > > To: harryproa@...
> > > > > Sent: Wednesday, January 14, 2004 4:29 AM
> > > > > Subject: [harryproa] Beams to windward hull
> > > > >
> > > > >
> > > > > How strong how light and of what material should the beams
> be
> > > > going
> > > > > to the weather hull on a 16' equal L an 8 ' beam ? I know I
> > know
> > > > its
> > > > > only 16' but thats all the room I have and can afford. I was
> > > > thinking
> > > > > of maybe a 16 or 18'' center walkway between the hulls and
> > two
> > > > > laminated 2x3s about two to three feet back from each bow
> > > > connecting
> > > > > the two hulls at each end. What do you think? To heavy, over
> > > > kill, or
> > > > > not strong enough?
> > > > >
> > > > > Todd
> > > > >
> > > > >
> > > > >
> > > > > To unsubscribe from this group, send an email to:
> > > > > harryproa-unsubscribe@...
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
> > > > Service.
> > > > >
> > > > >
> > > > > [Non-text portions of this message have been removed]
> > > >
> > > >
> > > > To unsubscribe from this group, send an email to:
> > > > harryproa-unsubscribe@...
> > > >
> > > >
> > > >
> > > > Your use of Yahoo! Groups is subject to
> > > http://au.docs.yahoo.com/info/terms/
> > > >
> > > >
> > > >
>
>
> To unsubscribe from this group, send an email to:
> harryproa-unsubscribe@...
>
>
>
> Your use of Yahoo! Groups is subject to
http://au.docs.yahoo.com/info/terms/
>
>
>