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.
> >
>
>
> >
> >
>
>
>