Subject: Re: [harryproa] Reducing beam afloat
From: Arto Hakkarainen
Date: 5/15/2008, 1:21 AM

--- Mike Crawford <> wrote:
> Rafael Francke at Cat2fold has a very interesting
> design for a folding
> catamaran that can reduce its beam while on the
> water.

> addition, he as a
> fold-down hard deck to span between the beams.
> You can see from the video how the scissors-action
> akas allow the boat
> to fold and unfold while stable, while also keeping
> each hull vertical
> (no stained/blistered topsides like with the Farrier
> method).
> This design would obviously make it tough to have
> a full-beam solid
> walkway. That would either have to be removable,
> foldable like the
> Francke design, or left out entirely.
> It wouldn't be a classic trailering solution,
> either.
> By putting the wheel in the cockpit, though, or
> using tillers, you
> could have a system that gets the beam down to 12'.
> That's narrow
> enough for a marina berth. 12' is also the maximum
> trailering width in
> the United States for getting a wide load permit
> that doesn't require
> escort vehicles with signs to lead or follow the
> main vehicle.
> There are problems with the design. It could add
> 50 to 100 kg to the
> boat weight, it would add expense, and there
> wouldn't be room for the
> wheels and walkway in the existing location. But if
> you want to fold on
> the water while keeping both hulls level, Francke's
> design is a workable
> solution.
[lot of text snipped from between]


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


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