----- Original Message -----

From: Robert

To: harryproa@...

Sent: Sunday, December 04, 2005 6:56 PM

Subject: [harryproa] Re: Polyprop honeycomb

I was looking at the shape and reckon it could be accommodated by
three conic sections without the revesse sheer and five conic
sections with. The top could always be mde from five separate
sections for the lw hulland about 8 or 9 for the ww hull. The joins
would be in places reasonably easy to fair into the rest of the boat.
I plan to make everything except the hulls first and so won't need to
hire a shed for such a long period. At the rate I'm going it will be
a while yet as I still haven't picked up any work in Darwin and so
far it is only to be my moey going into the boat.
Congratulations to all for the Visionarry rig. A lovely job with
specs almost too good too be true.
Robert
--- In harryproa@..., "Rob Denney" <proa@i...> wrote:
> G'day,
>
> Spoke to Bob August at Polycore yesterday.  He reckons vacuuming is
no problem, resin into the core is minimal. 
>
> I am not sure we (or anyone else) have the means to modify the
plans for the decks.  The lower part of the hulls is no problem, nor
is determining the half girths so the panel size is correct.  Where
it gets iffy is if and where the darts or scoring of the core are
required for the reverse sheer.  Given that Derek seems to do this by
trial and error on the first of any particular boat, then I can't see
us figuring it out. 
>
> All I can advise is to either wait until we have built one (I am
working on arranging this) or do it yourself, allowing generous
margins for cutting and shutting.  There is nothing to stop you
proceeding with the lower half hulls,  bulkheads, bunk bases, bunk
tops and cockpit seats (all of which can be built on the table),
beams, rig and rudders.  By the time you have completed these, we
will either have built one, or I will pay for one to be built so we
can sort out the top half.
>
> One thing I did find with my wing m,mast, and that is that the
bending should be done over a period of time, or else the core may
buckle.  No big deal, I left it (600mm long piece of 6mm thick with
200 gsm carbon on the inside) for a couple of hours at about 300mm
diam, then completed the bend to 90mm diam.  Thicker laminate will
probably make bending more reliable, maybe thicker core will as well.
>
> regards,
> Rob
>   ----- Original Message -----
>   From: Robert
>   To: harryproa@...
>   Sent: Thursday, December 01, 2005 9:09 AM
>   Subject: [harryproa] Re: Polyprop honeycomb
>
>
>   Checked out prices and engineering details of polycore.
>   2.6MPa compressive strength and 0.5MPa sheer seems pretty good
value
>   when 2/3 the price of Kiri strip and about 1/3 the weight.Even
after
>   the extra glass and possibly resin needed, this is cheaper and
>   lighter and should be easier for fairing and finishing. The
heavier
>   scrim with the pp film should reduce the compression of the scrim
and
>   reduce print through  at <10% difference in price. Possibly save
that
>   in resin. The 2.5MPa compression is well above the 0.1 of an
>   atmosphere so no troubles with distortion if using resin
infusion.
>   The hard part seems to be for Mark having to modify plans to suit
the
>   process.
>   --- In harryproa@..., "Rob Denney" <proa@i...>
wrote:
>   >
>   >
>   >
>   >   If using polyprop honeycomb, the vertical strip  as used by
>   >   Farrierlooks pretty good,
>   >
>   >   Yes, but glassing the bottom and topsides in one side full
length
>   on a table, then bending it to shape and glassing the inside will
be
>   quicker, easier and lighter.  The top section will require some
cuts,
>   so that may be easier in a mould or frames.
>   >
>   >   possibly even vacuuming into a female mould
>   >   if iit can handle vacuum.(though I don't find fairing concave
>   >   surfaces for female moulds easy).
>   >
>   >   Use a piece of conduit and glue the sandpaper to it.  Still
not
>   as easy as a male mould, but not too difficult. Keep the conduit
>   aligned fore and aft, but move it at 45 degrees.   Remember, it
only
>   has to be fair, not smooth.
>   >
>   >   It wouldn't necessarily have to be
>   >   a full atmosphere. It may be there is a happy medium that the
>   barrier
>   >   can handle.
>   >
>   >   Good point.  Experimentation will show this pretty quickly.
>   >
>   >   Is there much distortion of the honeycomb under vacuum?
>   >   Should not be, although the scrim between the cells will
probably
>   depress.  I suspect print through will be a problem as well.
>   >
>   >
>   >   On quantities:For a Harry it would probably need at least 50
>   sheets
>   >   so that wouldn't be a problem. Though in the short term I am
>   >   considering playing with some to make a dinghy and a fold up
>   kayak
>   >   but double handling and freight up to Darwin would probably
>   negate
>   >   joining in on a bulk buy
>   >
>   >   Fair enough, but when you place the small order try to
negotiate
>   a rebate for these sheets, when you place the big order
>   >
>   >   As the ww hull is so lightly loaded would you need more than
>   double
>   >   bias and a few stringers for any more than the centre of  the
lw
>   >   hull.
>   >
>   >   No. 
>   >   regards,
>   >
>   >   Rob
>   >
>   >
>   >
>   >
>   >
>   >
>   >   --- In harryproa@..., "Rob Denney" <proa@i...>
>   wrote:
>   >   >
>   >   >
>   >   > I have been told a few times by learned authorities that
>   schooner
>   >   rigs
>   >   > don't point well :-)
>   >   >
>   >   > Yesterday it was a Foundation 36 (well equipped quick  keel
>   boat
>   >   which they use for the Match Racing championships here). 
About 5
>   >   knots of breeze, we tacked behind him and climbed up and
past. 
>   Then
>   >   the breeze kicked in, and the new beam mounted rudder broke. 
Not
>   >   enough reinforcing onto the drum.  Easy enough to fix and
before
>   it
>   >   happened, we proved that beam mounted rudders do work. (13
knots
>   in
>   >   10 knots breeze).  Makes the boats even easier to build,
although
>   >   because of the small amount of bury on the rudder shaft, the
>   loads
>   >   are very high.
>   >   >
>   >   > I'm liking that polyprop honeycomb more and more. Certainly
for
>   any
>   >   > simple curves. I am not sure how much more expensive it is
and
>   have
>   >   > asked for pricing for comparisons but it has to win when
you
>   >   consider
>   >   > effort, weight and resiliance. There is the extra glass
needed,
>   >   > triaxial rather than double diagonal, and pssibly extra
resin-
>   >   though
>   >   > the choice of facing there shouldn't be too much difference.
>   >   >
>   >   > The polyprop does not soak up resin, as there is a barrier
>   between
>   >   the scrim and the honeycomb.  Not sure it would withstand
vacuum,
>   >   though.  The price of kiri has gone through the roof, so
polyprop
>   >   looks pretty good.  A discount kicks in at 50 sheets, so
maybe we
>   >   could combine a few orders and get it cheaper? 
>   >   >
>   >   > The bow section of the boats is not highly loaded.  You
could
>   use
>   >   double bias, with a strip of uni top and bottom and on each
side
>   back
>   >   to the beams, then triax between the beams. 
>   >   >
>   >   >
>   >   > regards,
>   >   >
>   >   > rob
>   >   >
>   >   >
>   >   >
>   >   >
>   >   >
>   >   >
>   >   >
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