-G'day Mike,
I am not sure what job I was about to do but the present one of
lecturing on plant physiology means I am supposed to be re writing a
prac manual instead of this email. It is actually challenging and
enjoyable.
I do not see why having the lw hull on its side prevents it
floating. There is the difficulty of providing steering. The best I
could come up with on that is a small removable electric outboard.
This is the hardest bit I have come up against.
regards,
Robert
-- In harryproa@yahoogroups.com.au, Mike Crawford <jmichael@g...>
wrote:
>
> 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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