Hi,
One thing to remember when thinking about folding
boats is all the extra bits and pieces that the bridgedeck carries. A Farrier
system can be relatively simple as it is only folding the amas and trampolines.
On Rare Bird we have walkways, steering lines, two outboard sleds, deck
boxes, anchor winch, sheet winch, trampolines, engine control lines, fuel lines,
lw hull wiring harness, a ramp, a longitudinal beam, cockpit with binnacle and
wheels, and overhead a sunshade. Of course you could take the Blind Date
approach and make the boat much simpler but you would still have outboard,
steering and walkways to contend with.
Making a Harrigami fold is difficult enough but a
sail onto the trailer Visionarry I suspect will remain a dream. It is a very big
boat. If you only intend to trailer a few times a year you may be better off
building a simple Visionarry with plug in beams and expect to spend a day or two
loading. Of course I would be delighted to be proven wrong.
Mark
----- Original Message -----
Sent: Monday, July 03, 2006 9:27 PM
Subject: [harryproa] Re: Mast
raising
Hey Robert,
How is the new job?
The support system you describe should work well if the lw hull
is stored upright next to the ww hull on the trailer. For a Visionarry,
though, that puts me about 20cm past the unescorted wide load limit, so one or
both hulls would have to get a bit narrower.
The idea of storing
the lw hull on its side, beneath the wing deck, makes supporting the ww hull
more of a challenge, but kills two birds with one stone: neither hull has to
change size, and the lw hull is already on its side ready for the mast.
It does get away from my dream of collapsing the boat on the water and
floating it onto a standard trailer, though.
Since the beams aren't parallel to each other and perpendicular to the hulls,
I'm having a hard time imagining how an Farrier-type system would work.
The same geometry would also make it difficult to use the Dragonfly
system. The only one that's making sense to me at the moment is the
cat2fold scissors system.
However, I'm sure there are other
ways to accomplish the goal. My only doubt involves a tilting/folding
system. Unless the trailer could take the boat out sideways, or I could
remove the mast while on the water, that could make it very difficult to
launch from anything other than a wide open ramp.
Is the dream
worth it in terms of added weight, complexity, and chances for failure?
I'm not so sure. Of course, my goal is to use the trailer only two to
four times per year, so that makes the inconvenience of box beams and a funky
trailer less of an issue.
Are there any photos, CAD images, or
links that describe Jim Shanahan's system in more detail? I
found a few references to it in early posts, but haven't seen anything that
describes how it works. One message mentioned something about being
lighter and stronger than conventional beams. If so, that would be
impressive. The righting aspect is also
intriguing.
-
Mike
Robert wrote:
-G'day Mike
I was
thinking on similar lines but don't se much problem holding up
the ww
hull. There is not an enormous weight off centre and a
vertical
bit of box section on the ww side triangulated at the base
should
provide enough support for the hull with a couple of tie down
straps to
hold it against. Either that and/or a support under the
junction of the
wing deck and hull. This would have to be to the lw
side of the c of
g.of the www hull on its own.
If the crossbeams had a temporary
controlling system such as a
farrier wishbone with a sleeve to allow
sliding of the crossbeam, or
even a complete folding system as designed
by Jim Shanahan then the
only difficulty is moving the lw hulls off the
trailer and onto a
trolley as everything else can be controlled with a
couple of
winches. Jim's system makes a lot of sense and would even
allow
righting from a complete overturning.
My personal preference is
to launch a folded system where the boat
can then be brought side on to
shore and the mast then inserted-
possibly with sail attached. The
crossbeams get winched out with
water supporting the system and you're
away.
I have tried to imagine taking the folded boat out onto the water
and inserting the mast from the water. It seems theoretically
possible but would probably be excessively difficult in
practice.
On another issue, I was wondering if there was any wat to
get round
the dependance on carbon for making a free standing mast
without
excessive weight. The closest I could come up with was , while
looking through a website on making bamboo fly rods, the testing of
tensile and compressive strengths and Young's modulus of strips of
bamboo. Rough calculations give a mast made of quality bamboo strips
a weight of about 2.5 times that of carbon. The technology for
utilising bamboo has come some way to making this practical, but
organising supplies off stream from flooring manufacturers would be
horrendous
Robert
-- In harryproa@yahoogroups.com.au,
Mike Crawford <jmichael@g...>
wrote:
>
>
> If you can keep that leeward
hull in place as it rotates from
> horizontal to vertical, then there
shouldn't be any problem with
the
> size of the mast. Given
the length of the beams, a #14 winch at
16:1
> should be enough
to bring the leeward hull into place with a 22m
wing
>
mast. Though I'm not familiar with the size of winches used on the
> Harry's, my guess is that you'll have at least a #14, which is the
> smallest self-tailing size offered by some vendors.
>
> If this is not enough, it would be simple to double the
purchase
with
> a block. If you want even more than 32:1,
then you could have a
single
> line going from the trailer to the
first beam, back to the trailer,
up
> to the second beam, back to
the trailer again, and then up to the
> winch. That might be
even be enough to lift your tow vehicle if
you put
> some muscle
into it..
>
> ---
>
> For me the
question then becomes how much help you're willing to
>
require. If you can get a few people to lend a hand, then the
Harrigami
> setup described in the article should be fine.
It's certainly the
> simplest and cheapest way to go, and there's a
lot to be said for
both.
>
> I'd probably
choose to spend more on a trailer to help ease the
> process,
though. This would be partially to save on boatyard
costs, and
> partially to allow two people to launch in areas that don't
necessarily
> have paid help.
>
> I
think even a Visionarry could be kept to an 11' / 3.3m
trailering
> width if the leeward hull could be stored on its side on the
trailer
> beneath the cockpit. My first thoughts on this
would be to:
>
> - Create a bunk that
could hold the ww hull upright on its own,
>
> - Create a detachable moving bunk for the
lw hull with its own
> wheels that could be lowered and used to move
the hull out away
from the
> trailer,
>
> - Add two long horizontal arms that could
be used to hold the
lw
> hull in place the proper distance away
from the ww hull, as well as
keep
> the trailer assembly together
when launching and retrieving the
proa,
>
> - Give the lw hull bunk assembly the
ability to pivot to
vertical
> without sliding towards the ww
hull and trailer,
>
> - Add some sheet
blocks to the trailer and akas through which
the
> winch line can
be run,
>
> - Add two short vertical
arms with soft rollers that could be
> inserted into the main trailer
and used to catch the beams as they
> rotate down to
horizontal,
>
> - Add some block
attachment points to the lw hull so that it
can be
> winched
tightly towards the ww hull once the beams are in place.
>
> I'm not exactly sure how this would be done in a real
world
situation,
> though.
>
> The bunk
keeping the ww hull vertical would need to be pretty
strong,
>
especially if it's going to hold everything in place while on the
road.
> Perhaps it could be supported while by the lw hull
bunk once it is
in
> place under the ww hull, and by a temporary
support arm under the
> cockpit when the lw hull bunk is away from
the main trailer.
>
> The lw bunk might need a
roller bearing and expansion arm/track
to
> support it until it
is moved far enough from center to get the
inboard
> wheels down
(assuming the outboard wheels can be dropped while the
> trailer is
still whole). The wheels would also need to pivot 90
degrees
> to make the transition from assembly to launch. Alternately,
there
> could be two sets of wheels, but that seems a bit
excessive.
>
> Ideas on how to improve this setup,
especially on how to make
that lw
> hull bunk work, are
welcome. I don't mind seeing my ideas trashed
as
> long as
something better results. Rob could probably solve this in
a
> weekend if I were actually building a boat, but I've got five years
left
> of lurking in this group before I get to that
stage.
>
> -
Mike
>
>
>
> oceanplodder2003 wrote:
>
> > Saw that, my concern was at what mast length would it become
an
issue,
> > considering that if I go for Rob's una rig I'm
assuming the mast
must
> > be taller, and I think Harry's is
longer than Harrigami to begin
with.
> >
> >
>
>
> >
> >
>
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