Subject: [harryproa] Re: Reducing beam afloat
From: Mike Crawford
Date: 5/16/2008, 12:26 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

<<If the hinge mechanism on the lw end was to ww of the rudders, and the ww end hinge was at the ww hull, it is possible to still have the rudders and bring the hulls adjacent.>>

  Yes!  How silly of me not to have noticed.  I was still in catamaran mode, where adding another foot or two of beam between the hinge and the hull would make the collapsed beam wider. 

  But with the cockpit of a Harryproa bulging out from the center of the ww hull, there might be just enough room for some rudders and a hinge.  It would definitely work if you add another foot to the collapsed beam.

  After measuring the current Harry image, it looks like the lw hull is 2.5' wide, while the ww hull is 8.2' wide.  If the ww hull/cockpit were extended to 9.5', that would yield a 5.75' cockpit  and a total beam of 12'.  Everything should just about work out.  This would make it easy to get the full 22' beam out of a 12' collapsed boat, without having anything protrude into the interior of the ww hull. 

  Just as important, it provides more flexibility in terms of beam variability on the larger boats.  Going from 14' to 27' would be a non-issue.

  Thanks, Robert.

       - Mike


Robert wrote:

-. The torque due to weight of the ww hull on the ww end with about
2' bury bury is about a fifth of the lw end and the bury on the lw end
is less than 3' for a harry. This can give another foot to play with.
I was looking at 10'wide ww and 4'wide lw( not quite sure how much
space is needed for the rudders). This gives 14' fully collapsed and
22 foot expanded with two foot bury. The bearing surfaces could be
epoxy-graphite or some low friction plastic with fair tolerances
except for the last wedging into position. They could be strapped into
position with some sort of cam lock such as on tie downs . Though
there are still the racking loads -Maybe take a leaf out of farriers
book and have some braces to anchor the ends with minimum bury-Exactly
the same braces as Farrier uses could be slotted in after expansion
and wedging. Theoretically, it could be placed in a shallow socket and
braced with spectra, It is done with masts all the time -but they do
occasionally fall over. I think I would feel more secure with about 2'
bury, well braced and strapped.

For a horizontal folding mechanisms. If the hinge mechanism on the lw
end was to ww of the rudders, and the ww end hinge was at the ww hull,
it is possible to still have the rudders and bring the hulls adjacent.
Jim Shanahan drew up a system that would work like this.

In harryproa@yahoogroups.com.au, Mike Crawford <jmichael@...> wrote:
>
>
> This discussion has helped clarify two things for me:
>
> a) I still prefer the scissors system for a variety of reasons,
> including the ability to radically reduce a boat's beam..
>
> b) Point A above may be moot.
>
>
> Rob has sold me on the idea of 360 degree beam-mounted rudders that
> kick up in both directions, and I don't see that working with a
scissors
> setup. Doh! Robert also makes a good point about using a series of
> blocks to collapse the system.
>
> It might also be possible to rig an expansion/contraction device that
> connects to the center of each hull and uses a combination of internal
> and external lines to move the two hulls apart or together. This could
> then stored in the lw hull when not being used. Now any worries of
> being able to expand/collapse singlehanded disappear.
>
> The beams would probably have to be rinsed and dried before
collapsing
> in order to keep out the salt and sand, but that's not too tough. The
> rudder mounts would have to on the outside of the the ww /external beam
> section, but that should also be easy to take care of.
>
> ---
>
> The real question is how wide and narrow can the boat be with
> telescopic beams. (the following dimensions are rough estimates)
>
> Let's take a Harry and expand the top of the ww hull a bit in
order to
> provide enough room in the cockpit for a wheel. A 9' ww hull comprised
> of a 6' cockpit and 3' lower section, next to a 3' lw hull, would yield
> a 12' beam when fully collapsed. The external beam section would then
> be attached to the ww hull, because it connects to the overhanging
> bunk/cockpit section, and the internal beam section would be
attached to
> the lw hull.
>
> Fully collapsed there would be 6' of beam between the hulls. If you
> want 3' of overlap between the beam sections, that only provides for 3'
> of expansion, yielding a total beam of 15'. That's a bit narrow.
>
> You might be able to get get another 3' of expansion by allowing the
> internal sections to extend into the ww hull when the boat is
> collapsed. It would be a bit inconvenient when trying to access the
> head while at a marina, but it could work. That would yield a total
> beam of 18', which is starting to approach the stock beam of 22'.
>
> Moving to a 14' beam when collapsed would yield an expanded beam of a
> full 22' (beams penetrate ww hull when collapsed), or 19' (beams never
> enter ww hull). 14' might be the beam of a 40'-50' monohull, and is
not
> hard to find at most marinas. It's also somewhat easy to transport a
> 14' wide boat by trailer, though since this would require an escort
> vehicle, it would be best done only once or twice a year.
>
> A 22' Harry could have a single 3' x 10' removable walkway between
the
> hulls, and that would probably be light enough to manhandle into and
out
> of position when collapsing (provided it's not done every day). As
Arto
> said, though, simpler is often better. As long as the cockpit is big
> enough, there's nothing wrong with all trampoline/netting between
the hulls.
>
> A Visionarry would probably require a collapsed beam of 16' to get an
> expanded beam of 26' if the beams extend into the ww hull when
> collapsed, or 18' to get to an expanded beam of 27' if the beams do not
> extend into the ww hull when collapsed. A 16' to 18' beam is still
> probably within reason for many marinas. It's definitely a lot better
> than 27'.
>
> Is 3' of overlap enough? Probably. That's the current bury of the
> beams into the lw hull, so it should work. I just wouldn't know how to
> do the analysis on the overlapping joint -- it has been too many years
> since I did torsion calculations, and I also don't know how square
> carbon beams would respond. That might be best left to a computer
> running a finite element analysis program.
>
> ---
>
> I still think that the scissors beams are the best option if you want
> the ability to take a Visionarry-sized boat down to a 12' to 14' beam
> when collapsed. But that would require either a lot of hassle with
> beam-mounted rudders, or more likely, hull-mounted rudders.
>
> On the other hand, if you want to expand and collapse on a regular
> basis, and want beam-mounted rudders, telescopic is the way to go.
>
> Since transportation over roads is part of my long-term plan, I could
> use either system on a Harry, but would have to go with a scissors
setup
> on anything with a larger beam.
>
> - Mike
>
>
>
> Peter Southwood wrote:
> >
> > Hi Robert,
> > I think it could go either way depending on the engineering. Farrier
> > has had great success with his hinged system, but there are not many
> > sliding systems that get used a lot (as far as I know, correct me
if I
> > am wrong) I will agree a poorly designed hinge/folding system is
> > easier to achieve by accident or lack of skill, and the devil is in
> > the details.
> > Cheers,
> > Peter
> >
> > ----- Original Message -----
> > From: Robert <mailto:cateran1949@...>
> > To: harryproa@yahoogroups.com.au
> > <mailto:harryproa@yahoogroups.com.au>
> > Sent: Thursday, May 15, 2008 11:53 AM
> > Subject: [harryproa] Re: Reducing beam afloat
> >
> > G'Day Peter,
> > Hinges are a pretty high stress concentration. I have my
doubts that
> > it is lighter than a sliding system. The sliding system has
really no
> > extra weight other than a bit of bearing surface. Maybe a few
> > kilograms at the most. Rob and Mark had no problems with
Elementarry's
> > sliding system with slightly thicker beam at full out and full in
> > allowing easy movement at other points. I would have thought
this was
> > easier to handle the racking loads as the highest stress is at the
> > beam/lw join where the scissor folding system has a hinge and the
> > sliding system is no different from the usual system.
Controlling the
> > sliding in and out could be done with two simple winches and
about six
> > small snatch blocks or a continuous line system.
> > Robert
> > -- In harryproa@yahoogroups.com.au
> > <mailto:harryproa%40yahoogroups.com.au>, "Peter Southwood"
> > <peter.southwood@> wrote:
> > >
> > > Hi Robert,
> > > Hinges for swinging are easier to get to work smoothly while
still
> > keeping stresses and play small than sliding beams, unless you
have
> > developed an improved sliding system that hs no play, can take
racking
> > loads, slides easily without jamming on both beams, and
prevents one
> > beam sliding in or out more than the other, which could lock
> > everything up, and still has fewer moving parts and critical
failure
> > points than swing hinges, and locks easily and reliably when
deployed
> > for sailing. Also should weigh less.
> > > Cheers,
> > > Peter
> > > ----- Original Message -----
> > > From: Robert
> > > To: harryproa@yahoogroups.com.au
> > <mailto:harryproa%40yahoogroups.com.au>
> > > Sent: Thursday, May 15, 2008 9:50 AM
> > > Subject: [harryproa] Re: Reducing beam afloat
> > >
> > >
> > > -A simple sliding in telescoping beams is pretty simple.There is
> > > plenty of bury available. three metre wide ww hull and only
> > narrowing
> > > by less than two metres, leaves a metre to play with. There
is a bit
> > > of fiddling to anchor the the ends but not insurmountable. The
> > > advantage, is there are no fancy hinges , just simple beams and
> > > sockets I don't see too many problems with sealing the
> > crossbeams, as
> > > the sockets could be separated from the inside volume, or just
> > wrap a
> > > boot around the point of insertion. I looked at folding systems
> > and I
> > > worked out how a folding system to trailing is possible. Just a
> > bit of
> > > drama in removing the mast, but not insurmountable. I felt
that if I
> > > had to trailer, then I can simply take the beams out, but I
> > could see
> > > situations where I would like to quickly narrow and still be
able to
> > > gently sail.
> > > Robert
> > > -- In harryproa@yahoogroups.com.au
> > <mailto:harryproa%40yahoogroups.com.au>, "Rob Denney" <harryproa@>
> > wrote:
> > > >
> > > > G'day,
> > > >
> > > > Cat to fold is an interesting solution. To get 3560
degrees on the
> > > tillers,
> > > > mount the rudders on the beams, although this may mess up the
> > > scissoring.
> > > > Could also put the rudders in the hulls in daggerboard cases,
> > if you
> > > really
> > > > wanted to scissor it.
> > > >
> > > > regards,
> > > > Rob
> > > >
> > > > >
> > > > >
> > > > > I am aware of cat2fold desing and actually thought it
> > > > > would be the best solution for a folding big proa.
> > > > > Trailering is not an issue for me. Accessing marinas
> > > > > is. The scissor-like mechanism of cat2fold design
> > > > > would probably offer most reliable and solid solution
> > > > > to folding while afloat. To get reasonable beam while
> > > > > folded steering wheels should be in the cockpit
> > > > > (tillers would be better but I haven't been able to
> > > > > figure out how to get 360 degrees rotation functional
> > > > > with tillers). Rigid walkway and optional dingy ramp
> > > > > would be hard to fit to folding option though. They
> > > > > would be very nice but I haven't been able to figure
> > > > > out those details yet. One monohull design had
> > > > > removable walkway part of cockpit bottom that doubled
> > > > > as gangplank. Perhaps removable/folding walkway and
> > > > > dinghy ramp that can be lowered while folded. Two
> > > > > gangplanks that can be attached between hulls as
> > > > > walkway? Or perhaps just live without the added
> > > > > complexity... Just remembered the KISS principle
> > > > > again.
> > > > >
> > > > > Arto
> > > > >
> > > > >
> > > > >
> > > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > ----------------------------------------------------------
> > >
> > >
> > > No virus found in this incoming message.
> > > Checked by AVG.
> > > Version: 7.5.524 / Virus Database: 269.23.16/1433 - Release
Date:
> > 2008/05/14 04:44 PM
> > >
> >
> >
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> > No virus found in this incoming message.
> > Checked by AVG.
> > Version: 7.5.524 / Virus Database: 269.23.16/1433 - Release Date:
> > 2008/05/14 04:44 PM
> >
> >
>

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