we have those wavepiercer bows on the newest A class. Morelli & Melvin have
quite an extreme version but in an article said they'd never do it on a larger
design. It only works on small beach cats because of the crew's ability to get
the weight aft. On a larger boat they'd be very susceptible (sp?) to nose
diving.
------ Original Message ------
Received: Sun, 22 Jan 2006 09:08:03 AM MST
From: "Robert" <cateran1949@yahoo.co.uk>
To: harryproa@yahoogroups.com.au
Subject: Fw: [harryproa] Re: sailing Elementarry
Quite correcct. Limit of power. Speed of assembly is an important
factor. You can cover a lot of ground in those extra minutes spent
rigging. Light air performance is probably the greatest advantage as
you can get up into cleaner air. Still reckon the schooner will do it
for top speed unless you can get your backside further aft.
Continue to onder if the latest Nacra type bows with fatter down
below and less height may provide earlier bouyany forward and be
slightly slipperier through the water in the intermediate stage.
Again , getting your backside futher aft would be a lot easier.
I am not quite sure if I am on the same planet as those who persist
in a lw pod for a sailing proa. Am I missing somethingin my
understanding of hydrodynamics and hydrostatics. My calculatons for
the hydrostaics show the boat has a greater tendancy to keep going
over if slightly >90degrees as the ww hull is more likely to go paast
top dead centre. But then again, the mast is not designed for those
loads in Jzerro.
Regards,
Robert
>
> G'day,
>
> The diagonal stability is the limit on the power, not the speed,
but on the face of it, you are correct. The lower coe will mean less
nose diving. However, there will be a weight aloft saving (as well
as a weight overall saving) which is a plus for the una rig and
speed overall. There is also more twist (thus lower coe) in a
higher rig, as well as better light air performance. Won't know all
the trade off until we try it. Thje una rig will certainly be
quicker to rig, which is a concern as well.
>
> Should also note that with 22 sqm of sail, my El is definitely a 2
person boat in a breeze. A crew will definitely increase the breeze
at which it falls over.
>
>
>
> regards,
>
> rob----- Original Message -----
> From: Robert
> To: harryproa@yahoogroups.com.au
> Sent: Friday, January 20, 2006 10:20 AM
> Subject: [harryproa] Re: sailing Elementarry
>
>
> For Elementarry , the limit on speed seems to be the forces that
bury
> the bow: drag on lw hull, height of coe of sail power, fore aft
> righting moment. Making fatter or taller bows to improve fore aft
> righting moment may not do any good as it increases drag (In fact
> Nacra have gone the other way and chopped off the top of their
bows
> but kept or possibly increased the lower bouyancy); Going longer
> means a bigger boat; reducing depth and drag of rudders should do
> something; replacing a schooner rig with a una rig will lift coe
of
> sail power and make it worse, unless through increased efficiency
of
> the rig there is less drag on the hull and foils in preventing
> leeway. Can't see it myself unless you go to wing.
> Regards
> Robert
>
>
> --- In harryproa@yahoogroups.com.au, "Rob Denney" <proa@i...>
wrote:
> >
> >
> > G'day,
> >
> > Not much difference in speed, although I have no real numbers
to
> compare as I have not used an Easyrig on Elementarry. Cost is
> probably similar, the easyrig maybe a little cheaper. Ditto ease
of
> construction. I would be quite happy cruising with either.
Suspect
> neither is as fast as a wingmasted una rig, which is the next one
to
> try..
> > I found it was easiest to drop the jib and sail with the main
> only when I needed to reef. This would not work on the schooner
where
> the aft sail would be reefed first. It is pretty easy to sail
the
> schooner on the front sail, very difficult on the rear one.
> >
> > Polycore butt joins with bog or nothing. It will require a
lot
> of resin to fill the gap if infusing so some form of filling is
> probably required.
> >
> > Compounding Polycore may be possible with an iron, or with
> slits. Need to do some tests to see.
> >
> > Regards,
> >
> > Rob
> >
> > I must admit the schooner rig appeals to me as well, though
when
> I pushed Rob
> > he seemed to favour the easyrig (Harry) and after all it's
his
> baby and he
> > probably has more time sailing both rigs than all of us. What
> happens to the
> > balance of the easy rig with two reefs, or if you are running
> with the main
> > down in heavy air?
> > Would really appreciate a detailed comparison of the two with
a
> few numbers
> > thrown in (speed, cost, ease of construction).
> > Another question about the poly-core, how do you do butt
joins?
> how do you
> > form compound shapes? Sorry if this makes me sound like a
Wally
> who knows
> > nothing but it's big project for me.
> > Cheers
> > David
> >
> > ------ Original Message ------
> > Received: Tue, 17 Jan 2006 09:26:03 AM MST
> > From: "Robert" <cateran1949@y...>
> > To: harryproa@yahoogroups.com.au
> > Subject: [harryproa] Re: sailing Elementarry
> >
> > For cruising I still prefer the schooner rig. Yes extra
sheets
> and
> > sheet loads but you can bring sails closer to deck as you
don't
> need
> > clearance for the forward part of the boom and you can couple
the
> > sheets and use a small winch. Overall significantly lower c
of e
> of
> > rig and therefore less capsizing moment for given sail area.
Also
> for
> > shallow water sailing there is some directional control with
just
> the
> > sails. Whether to go for a wingmast or a round mast with
pocket
> luff,
> > I am ambivalent. Wing mast probably more efficient but I like
> > simplicity and reliability of pocket luff, Wharrams are
pretty
> happy
> > with them (OK I know that is not necessarily an argument
about
> how
> > well they sail but it is an argument over there reliability)
I am
> > even tempted to go for a Wharram type gaff rig only using a
> nicely
> > curved carbon tube for the top spar. I like the idea of the
> unstayed
> > wishbone boom
> >
> > Down wind for cruising it has to be a kite. Lifting bows
instead
> od
> > depressing them. On a long downhill section put all other
sails
> away
> > and relax unless you want to get that little bit more out of
the
> kite
> > by figure of eight flying. No worries about leaping off the
top
> of
> > the wave and plowing into the back of the next one, stalling
and
> > pitchpoling as you haven't let go of the screecher in time
and
> the
> > apparant wind has doubled. With a kite your bows stay up and
if
> you
> > do stall into the back of the next wave the kite will pull
you up
> > insead of over --- In harryproa@yahoogroups.com.au, Mike
Crawford
> > <jmichael@g...> wrote:
> > >
> > >
> > > For going fast, I'm more a fan of Rob's schooner rig than
the
> > easyrig.
> > >
> > > This is partially because there are no concerns about
> forestay
> > > tensions, and fewer concerns about rig stiffness, and
mostly
> > because it
> > > provides for more sail area, with better foil shapes, and a
> lower
> > center
> > > of effort. When tacking downwind in light wind, two
battened
> foil
> > > shapes are going to generate more lift than a main and jib,
and
> > when
> > > running the schooner could present quite a wing-on-wing
profile.
> > >
> > > The schooner rig will require more winch work than an
> easyrig,
> > but
> > > only when lazy sailing. if you want to be competitive,
you'd
> need
> > all
> > > sorts of additional strings on an easyrig anyway. I'd
rather
> go
> > with a
> > > pair of extra-tall mainsails for light wind, and reef them
in
> > normal
> > > wind, than to try to stiffen an easyrig with running stays
and
> > attempt
> > > to fasten additional headsails.
> > >
> > > ---
> > >
> > > Speaking of rig stiffness, I do feel the need to weigh in
on
> the
> > > comments about Rare Bird's rig. Yes, it's pretty
flexible.
> > However, as
> > > the owner of a lightweight 27' cat, which can only be
righted
> by
> > another
> > > boat if capsized, I can appreciate a rig that will allow
some
> of
> > the
> > > gust energy to pass by the boat. Going over on a beach cat
or
> > > Elementarry is wet and inconvenient. Going over on a 9+
meter
> boat
> > is
> > > tremendously uncool.
> > >
> > > If you've got everything right on the edge, with the
windward
> > hull
> > > just skimming the water, it takes *very* little extra gust
> energy
> > to
> > > suddenly whip the boat over. The only solution is to be
> lightning
> > quick
> > > with the mainsheet, but that's a tall order if you're going
to
> be
> > doing
> > > it for more than ten minutes at a time. Flying a hull is
great
> > fun, but
> > > any look at the Stiletto nationals will turn up some boats
that
> > didn't
> > > hold that fine balance in a gust. Even the skippers of the
> > Reynolds 33
> > > lose it now and then.
> > >
> > > When cruising, going past this edge is entirely
> unacceptable.
> > It's
> > > much better to have a flexible rig, with the addition of
> perhaps an
> > > outleader kite, than to risk gust-induced capsize (fool-
induced
> > capsize,
> > > of course, is rig-independent).
> > >
> > > When racing, though, there's still something to be said
about
> a
> > boat
> > > that can handle the gusts. Let's say you can fly a hull
with
> 40 sq
> > m of
> > > canvas with a stayed rig, and 50 to 60 sq m of canvas with
a
> more
> > > flexible rig. The flexible rig provides two advantages.
> First, in
> > a
> > > gust, the flexible rig will either allow you to keep
sailing
> > without
> > > adjustments, or give you lots of time to adjust, while the
> stayed
> > rig
> > > will require quick reflexes in order to avoid a capsize.
> Second,
> > those
> > > extra 10 to 20 sq m of canvas will come into play nicely
in
> the
> > lulls,
> > > do so automatically, while the stayed rig will need to
either
> > unreef or
> > > hoist an extra sail to keep up.
> > >
> > > Supporters of a stayed rig will point out that the extra
> canvas
> > will
> > > create extra drag, so in theory the stiffer rig will beat
the
> > flexible
> > > rig in some conditions. This is true. But a capsized boat
> > eliminates
> > > all rig advantages. Besides, we don't all sail in exactly
15
> knots
> > of
> > > trade winds, and changing wind conditions will likely favor
the
> > extra
> > > sail area and self-adjusting nature of the flexible rig.
> > >
> > > ---
> > >
> > > The one change I would make would be to go with an
unstayed
> > wishbone
> > > rig like they have on the Wyliecats.
> > >
> > > http://www.wyliecat.com/info/wishbone_rig.html
> > >
> > > One adjustment line automatically handles sail shape,
leech
> > tension,
> > > and mast bend, with very little stress on the boom. Sail
> shaping
> > is
> > > very quickly done, the boom creates its own lazy jack
pocket
> when
> > taking
> > > the sails down, and a reduction in heeling moment can be
> achieved
> > either
> > > by reefing, flattening, or both, allowing for some quick
sail
> > > adjustments for a minimal amount of time and effort.
> > >
> > > However, I've never sailed a Wyliecat, so I can't speak
from
> > > experience. I just love the idea of it.
> > >
> > > - Mike
> > >
> > >
> > >
> > > dominiquebovey wrote:
> > >
> > > > Hi,
> > > >
> > > > Boats as light and canvassed as HP's mostly sail "close-
> hauled"
> > due to
> > > > their high speed, so they need a rather flat sail
profile.
> But to
> > > > start you need a hollow profile, so the sail should be
> tunable
> > quickly.
> > > >
> > > > I would see a 8.5m proa (maximum of M2 class) for 3 crew
> (minimum
> > > > number for racing on Lake Geneva), with easyrig, around
30-
> 40m2
> > sail.
> > > > I am persuaded the easyrig is OK for racing, provided it
is
> stiff.
> > > >
> > > > One of the crew would be adjusting the sail permanently
> (making it
> > > > hollower in the lulls, flattening it when speed
increases).
> > Another
> > > > crew would be running up/down the tramp to keep the LW
hull
> just
> > above
> > > > the water, and the 3rd one steering.
> > > > And all crew could be going on trapezes when needed. So
you
> need
> > > > running sidestays which can be attached to several
selectable
> > points
> > > > on the WW hull or on the beams.
> > > > To go on trapeze, you unhook them off the boat, and hook
them
> on
> > your
> > > > trapeze pants/harness whatever-the-word-is.
> > > > Naturally the rig must be self supported without the
runners,
> for
> > easy
> > > > cruising.
> > > >
> > > > I know it is quite a new boat, something between
Harrigami
> and EL,
> > > > with more displacement. The Elementarry lw "sinks" about
1cm
> for
> > 15kg,
> > > > for the 8.5m the figure should be 20-25kg, so a less fine
lw
> hull.
> > > > The Elementarry is unfortunately a little too light for 3
> racing
> > crew
> > > > I am afraid, as we discussed last year.
> > > >
> > > > Regards
> > > > Dom
> > > >
> > > >
> > > > --- In harryproa@yahoogroups.com.au, "Rudolf vd Brug"
> > <rpvdb@f...> wrote:
> > > > >
> > > > > Hi,
> > > > >
> > > > > Possibly the difference in sheeting in between you and
the
> > Tornado
> > > > lies in the fact that they where flying a spinnaker.
> > > > > That sail is so much fuller in shape it would redirect
the
> wind
> > > > passing it much more than a flatter sail (or no sail at
all)
> > would.
> > > > >
> > > > > Some time ago I read an interesting article on a una
rigged
> mono
> > > > with a wing mast. It was designed not to fly downwind
extra's.
> > > > > The owner did have a gennaker but it only gave him one
knot
> of
> > extra
> > > > boat speed. It was concluded the tighter sheeting angle
of
> the
> > main
> > > > might be responsible for this. The gennaker would
generate so
> much
> > > > disturbance of the air passing at the leeward side it
doesn't
> > attach
> > > > to the main any more. Therefore the main doesn't generate
> lift as
> > it
> > > > does whith no head sail in front and is only producing
drag
> which
> > > > helps downwind but not as much as lift would.
> > > > > ----- Original Message -----
> > > > > From: Rob Denney
> > > > > To: harryproa@yahoogroups.com.au
> > > > > Sent: Monday, January 16, 2006 2:19 PM
> > > > > Subject: Re: [harryproa] Re: sailing Elementarry
> > > > >
> > > > >
> > > > > G'day,
> > > > >
> > > > > Not sure the kite would have helped much as the
apparent
> was
> > well
> > > > forward of the beam. Still intend to try it because they
are
> such
> > > > great fun. Interestingly, the Tornado was strapped in
hard,
> > traveller
> > > > on the centreline, whereas i was quite eased on the same
> point of
> > sail
> > > > and at the same speed. Lots to learn...
> > > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > ----------------------------------------------------------
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> >
> >
> >
> >
> >
> >
> >
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