Subject: [harryproa] Re: Current rudder design? |
From: Mike Crawford |
Date: 5/30/2008, 10:05 AM |
To: harryproa@yahoogroups.com.au |
Reply-to: harryproa@yahoogroups.com.au |
Its just finding the correct geomtry to allow specific sail being
Two sets of everything is more complex. There's a lot to be said for
a single una rig that doesn't have to be messed with.
With that said, a schooner rig will:
- allow more sail area for the same righting moment
- provide a backup in case one mast/sail fails
- use shorter/lighter masts that are more easily stepped, and also
transported/
- allow you to steer and sail the boat, even if both rudders are gone.
- provide a great weathercocking setup using a reefed aft sail in a
big storm (assuming you're not using drogues yet).
It's all a matter of what you want to do with the boat, how far out
you want to go, and how long you'll be there. One person's hassle is
another person's peace of mind.
- Mike
tsstproa wrote:
used to feather through Aframe if back winded.
I see where you would think having two sails would make it easier to
set for any condition in deep water.
But what could be easier than one line to reef sail and another to
shift entire sail from fore to aft. Instead of worring about two
sets of everything.
Todd
--- In harryproa@yahoogrou
wrote:
>
> If the sails were as easy to shunt and good in being caught aback,
I
> would be with you all the way. I intend to set up a system similar
to
> your A frame on my 5m outrigger proa using a windsurfer rig. It is
> designed for paddling out to snorkeling and fishing spots, and it
> would be nice to sail home when the wind gets up.
>
> When you are in deeper water with a schooner rig, you power up. You
> are not feathering all the time
> Robert--- In harryproa@yahoogrou
> wrote:
> >
> > I don't know less depth less likely to hit somthing. Sounds
good
for
> > cruising or racing. Also smaller boards possibly working
under
less
> > strain on structure.
> >
> > Also one sail less gear along with shorter board depths =
less
drag
> > What a waste to have one sail feathering in the wake of
another.
> >
> > Better balance faster foward speeds with least amount of
forces
all
> > around.
> >
> > Todd
> >
> > --- In harryproa@yahoogrou
> > wrote:
> > >
> > Whether to
> > > have the hassle of a large rudder or the hassle of
moving the
sail.
> > > For skinny water, but for deeper water, I would
> > > prefer the deeper foils.
> > > I feel the two masted set up can achieve both, though
not as
> > > elegantly as Todd's system, as the forward sail is about
1/3
back
> > and
> > > you can leave the aft sail feathered: simply not driving
it as
> > hard in
> > > skinny water.
> > > I think for Doug's boat, if the ww hull is a little
heavy for
the
> > > system, you could narrow the beam or put some of the
gear in
the lw
> > > hull. I'd make sure the foils were near perfect first.
If
there are
> > > significant imperfections, the foils will stall too
easily.
Maybe
> > put
> > > those lumps on the leading edge, as found on humpback
whales,
which
> > > prevent stalling.
> > > Robert
> > >
> > > -- In harryproa@yahoogrou
wrote:
> > > >
> > > > Hey Doug ,
> > > >
> > > > In reference to sail/sails. If you could get any
single sail
> > with in
> > > > reasonable size for your boats length and weight
with its
> > leading
> > > > edge at about 1/4-1/3 the way back from foward bow,
and
trailing
> > > > edge of sail no further back than 5/8-3/4 from
foward bow
on
> > > > leeward hull. Your boat would have amazing handling
and with
the
> > > > lightest helm you could have ever imagined. With
less hassle
of
> > the
> > > > two sails. I'll steak all the boats in my back yard
and all
my
> > > > models. I Would have said reputation but whats that
but pop
> > culture
> > > > None valued to me. If I'm wrong come tak'em all,
there
yours!
> > This
> > > > will allow the use of your current boards as is
instead of
> > needing
> > > > to place them closer to the bows.
> > > >
> > > > Here are my two solution in getting sail area to
the correct
> > > > location for both tacks for both bows. One evolved
from the
> > other.
> > > > One balances traditional the other modern.
> > > >
> > > > http://www.youtube.
> > > > http://www.youtube.
> > > > http://www.youtube.
> > > >
> > > > Todd
> > > >
> > > > --- In harryproa@yahoogrou
> > wrote:
> > > > >
> > > > > I do feel the effect of letting the rear sail
off a bit to
> > help
> > > > when the wind is light or somethign ==.
> > > > > drag was the main issue though for the
brackets not going
near
> > the
> > > > water. Not just out of the water but a long way up
high to
be
> > sure
> > > > of not catchin gin a big wave washing up along the
bow. Just
> > ease of
> > > > mind, to have no possible achillies heels.
> > > > >
> > > > > Doug
> > > > >
> > > > > --- On Wed, 28/5/08, Robert cateran1949@ wrote:
> > > > >
> > > > > From: Robert cateran1949@
> > > > > Subject: [harryproa] Re: Current rudder design?
> > > > > To: harryproa@yahoogrou
> > > > > Date: Wednesday, 28 May, 2008, 7:30 PM
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > Hi Doug,
> > > > > I always wondered why you couldn't make the
brackets
angled
> > lifting
> > > > > foils, though there is so much reserve
righting moment
that I
> > can't
> > > > > imagine I would push it that hard. I would be
quite happy
to
> > cruise
> > > > > along at 25 knots ;>)
> > > > > My understanding is that if the rear rudder is
holding the
> > boat
> > > > from
> > > > > luffing up but is near the edge, then you can
always use a
> > little
> > > > > front rudder to steer- providing it is set up
to do so. If
> > this is
> > > > > happening in strong winds and messy seas, then
you can
drive
> > the
> > > > > foresail more than the rear one to change the
balance. If
> > there are
> > > > > greater difficulties in light winds, then
having the
rudder
> > further
> > > > > back won't improve things, but you can load
the rear sail
more
> > than
> > > > > the fore or put the front rudder down a
little. Having a
> > really
> > > > clean
> > > > > accurate foil can also do wonders.
> > > > > Your boat is relatively heavy on the ww hull
and that
could be
> > > > > contributing.
> > > > > Robert--- In harryproa@yahoogrou ps.com.au,
Doug Haines
> > doha720@
> > > > >
> > > > > wrote:
> > > > > >
> > > > > > Hi robert,
> > > > > >  
> > > > > > I'm imagining how high you need to
keep it on a big
boat
> > in a
> > > > big
> > > > > sea. Ijust start to get splashes of spray
sometimes now
where
> > the
> > > > beam
> > > > > comes off the side. I haven't been sailing out
in the sea
much
> > for
> > > > a
> > > > > long time though. There isn't any slowing for
me, but I
> > understand
> > > > the
> > > > > concensus was there was noticeable drag on the
old side
mount
> > style
> > > > > eg, elementarry racing etc. It looks like a
possible cause
of
> > pitch
> > > > > poling when you start to push the bow down. It
makes you
worry
> > > > about
> > > > > attaching rudders higher up. Eg new beam
siting. (PS I
still
> > reckon
> > > > > the beams may not be far aft enough to get
good response)
> > > > > >  
> > > > > > Dopug
> > > > > >
> > > > > > --- On Tue, 27/5/08, Robert
cateran1949@ ... wrote:
> > > > > >
> > > > > > From: Robert cateran1949@ ...
> > > > > > Subject: [harryproa] Re: Current
rudder design?
> > > > > > To: harryproa@yahoogrou ps.com.au
> > > > > > Date: Tuesday, 27 May, 2008, 8:12 PM
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > -Hi Doug,
> > > > > > I was wondering if you felt the boat
slow down
> > significantly
> > > > at the
> > > > > > moment when the rudder supports went
through waves.
> > > > > > I actually did mean to lock off the
rear and steer
with
> > the
> > > > front.
> > > > > > Theoretically there would be much
less load on the
tiller
> > and
> > > > better
> > > > > > response.
> > > > > > Robert
> > > > > > -- In harryproa@yahoogrou ps.com.au,
Doug Haines
doha720@
> > > > > wrote:
> > > > > > >
> > > > > > > Hi Robert,
> > > > > > >  
> > > > > > > I think there is a lot
of drag on the side
> > mounted
> > > > rudders. I
> > > > > > managed tp keep the connection to
hull up fairly high
but
> > > > still could
> > > > > > do with more clearence. It is very
unpleasing to see
> > water go
> > > > any
> > > > > > where near the front gear.
> > > > > > > Also I don't know about
steering with the
front
> > > > rudder, I think you
> > > > > > meant lock off the front and steer
with the backone.
> > > > > > >  
> > > > > > > Doug
> > > > > > >
> > > > > > > --- On Mon, 26/5/08,
Robert cateran1949@ ...
> > wrote:
> > > > > > >
> > > > > > > From: Robert
cateran1949@ ...
> > > > > > > Subject: [harryproa] Re:
Current rudder
design?
> > > > > > > To: harryproa@yahoogrou
ps.com.au
> > > > > > > Date: Monday, 26 May,
2008, 3:29 PM
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > -There are various
iterations, depending on
> > boat.
> > > > The earlier
> > > > > ones are
> > > > > > > attached to the side of
the hulls and work
well
> > but
> > > > add to the
> > > > > > > complexity of the hulls
and possibly drag (I
am
> > not
> > > > so sure
> > > > > that they
> > > > > > > add significant drag and
would be quite
happy
> > with
> > > > them). These
> > > > > > > rudders had 270 degrees
maneuverability.
They
> > can be
> > > > seen quite
> > > > > > > clearly on the harryproa
website on 'rare
bird'
> > > > and 'aroha'.
> > > > > Rob has
> > > > > > > been working on beam
hung rudders, playing
> > around
> > > > with them on the
> > > > > > > little Elementarry, and
you can see how they
> > have
> > > > developed in
> > > > > some of
> > > > > > > the files and photos.
They are designed for
360
> > > > degrees. He has
> > > > > done
> > > > > > > some finite analysis
engineering to work out
the
> > > > stresses to
> > > > > make sure
> > > > > > > the mounts are strong
enough. From what I
can
> > > > gather, the beam hung
> > > > > > > rudders can be lifted
for skinny water or
swung
> > out
> > > > of the way.
> > > > > They
> > > > > > > also have means of
kicking up either
direction
> > if
> > > > necessary. If the
> > > > > > > motors are placed on the
rudders it becomes
more
> > > > difficult to
> > > > > retract
> > > > > > > them for skinny water.
The rear rudder is a
> > large
> > > > part of the
> > > > > leeway
> > > > > > > resistance and therefore
need they need to
be
> > fairly
> > > > > substantial and
> > > > > > > strong. Some find it
useful to lock the rear
> > rudder
> > > > and steer
> > > > > with a
> > > > > > > partially lifted front
rudder. For tight
> > maneuvering
> > > > the two
> > > > > rudders
> > > > > > > together allow you to
crab or spin in
circles.
> > The
> > > > early
> > > > > rudders had
> > > > > > > the toe leaning forward
to allow balance.
This
> > may
> > > > have helped in
> > > > > > > avoiding ventilation.
> > > > > > > Robert - In
harryproa@yahoogrou
> > > > ps.com.au, "gardnerpomper"
> > > > > > > gardner@
> wrote:
> > > > > > > >
> > > > > > > > Hi,
> > > > > > > >
> > > > > > > > Is
there any information
(sketch or
> > > > drawing,
> > > > > preferably) of the
> > > > > > > > current
rudder design? This is
one
> > of
> > > > my areas of
> > > > > concern, and
> > > > > > I would
> > > > > > > > like to
see what the current
> > thinking
> > > > is. Specific
> > > > > questions are:
> > > > > > > >
> > > > > > > > what
are the dimensions of the
> > rudders?
> > > > > > > >
> > > > > > > > are
they designed to lift in
the
> > rudder
> > > > assembly for
> > > > > shoal draft
> > > > > > > >
sailing, or do they tilt?
> > > > > > > >
> > > > > > > > Do they
need 360 degrees
> > > > maneuverability, or just +/- 45
> > > > > > degrees from
> > > > > > > > the
direction of motion? (i.e
335-
> > 45
> > > > degrees, and
> > > > > 135-225 degrees,
> > > > > > > >
relative to the hulls)
> > > > > > > >
> > > > > > > > I am
specifically speaking of
the
> > > > charter proa, but I
> > > > > am curious if
> > > > > > > > the
basic rudder design applies
to
> > > > pretty much any
> > > > > size harryproa.
> > > > > > > >
> > > > > > > > Thanks,
> > > > > > > > -
Gardner
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
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> > > > > > >
> > > > > > >
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