Subject: Re: [harryproa] Re: Aerodynamics and sailing performance
From: "Rob Denney" <proa@iinet.net.au>
Date: 3/4/2007, 8:15 AM
To:
Reply-to:
harryproa@yahoogroups.com.au

 
G'day,
 
Like I said, lets compare apples and apples.   You will not find a near new 12m/40' cat with the same level of finish and gear as Rare Bird for less than $Aus500k.  I do not consider second hand Wharrams to be in the same category in regards to performance, comfort, usable space, ease of sailing or ease of maintaining, and probably not as well finished, built or equipped.
 
For evidence of built costs and time, I can do no more than point you to Harrigami, which took me 500 hours to build and cost $4,500 in materials, including the rig.  If you can build a cat of similar space, comfort, etc, then go ahead, you will make a lot of money. 
 
The Transpac should be a lot of fun, although the record is held by Steve Fossett in an Open 60 trimaran, so not sure I will be breaking it.  Hope you can get to SF in June next year and come for a sail. .
 
regards,

Rob   


Hello Rob,

On your 12 and 15 meter boats and the why you have in the past
desribe the build process and minimal materials used in the
construction with almost no high $ hardware and rigging to sail the
craft they would be alot less coastly than what I have seen so far.
Other wise whats the point? Minimum this and minimum that with the
same performance as a cat with less space at the almost the same
price. I believe shunters should blow away most production cats and
tris at 1/10 the cost at any length. Reynolds has a cat at first run
they were around 33 now 133$ maybe even more now , wow...

Not really intrested in the 7 meter performance boat but with the
sail area to weight i'd expect A class cat performance but maybe i
got the weight wrong.

As far as proffesoinal built traditional shunters. There's just no
market for them yet. Maybe there will be when you smash the record
in the transpac race. whoo hoooooo:)

If a single dominate leeward hull shunter can't do aleast 1 to 1 1/2
times the wind speed when its windy enough to sail above 10 knots,
then why bother. Unless your just into having the most unique craft
in the harbor with the least amount of room for the most coast per
length of hull with minimum amount of equipment and hardware.

Just seen a wharram 40' on yacht world for 35$ a 52 for 105$us and a
63' for 200$us. Granted probably with the performace of a
cuiser/race mono hull of same length but with a lot more space and
equipment/hardware required to sail the craft.

Todd

- In harryproa@yahoogroups.com.au, "Rob Denney" <proa@...> wrote:
>
> G'day,
>
> I have yet to see a professionally built "traditional design,
shunting outrigger canoe" (tdsoc)with 2 double bunks, sheltered
cockpit, showroom finish and hot and cold running water. I suspect
that if you paid someone to build you one it would cost a lot more
than a Harry.
>
> If you are referring to Elementarry, the same applies, although
the specs are different. The one for sale is a performance version
and performs as well as a traditional Tornado, is immaculately built
and finished and has a telescoping trailer and a 3 hp outboard. It
is for sale for $Aus16,000/$US12,000 (the owner wants a bigger
harry). A Tornado to similar spec would cost more than double
this. Even a mass produced Hobie 16 (slower, heavier, far more
complex) costs more than this. To compare performance with a tdsoc,
I would need to see some performance figures upwind and down as well
as on a reach. Rather than 'best guesses', these figures should be
comparisons from sailing against known race boats. To compare price
with a tdsoc, we need to find a professionally built tdsoc on a
trailer, with an outboard.
>
> If you compare apples with apples, I think you will find the
harrys are indeed cheaper than tdsoc. In fact, I suspect that the
reason there are not more pro built tdsoc's is because a) they are
too expensive and b) they do not perform well enough. I may be
wrong here, would welcome any information on professionally built
trad designed shunters, or why there are not more of them. You may
like to check on the proa_file chat group to see if there are any
such boats.
>
> I also dispute the 1.5 times windspeed claim. In light air (0-6
knots), this is very hard to prove as the breeze speed varies so
much. At the top end of moderate breezes (7-12 knots), you are
claiming a top speed of 18 knots. I have once achieved this speed
(by gps) in Elementarry, in a good deal more breeze than 12 knots.
I have never seen reliable proof that any canoe has regularly
achieved such speeds, much less in moderate air. Above 12 knots,
you are either dreaming, or are sitting on a boat which is as fast
as a very highly optimised, wing sailed C class cat. I would need
a lot more proof than has so far been shown to believe this is the
case. I would also like to see how well the tdsoc does to windward.
>
> Regards,
>
> Rob
>
> ----- Original Message -----
> From: Todd
> To: harryproa@yahoogroups.com.au
> Sent: Saturday, March 03, 2007 4:26 AM
> Subject: [harryproa] Re: Aerodynamics and sailing performance
>
>
> I don't Know minimal materials,break through in the building
> proccess minimum build time required etc..... This is what Rob
> preaches as soon as any one mentions traditional design. Knowing
> that a shunting outrigger canoe needs minimal amount of anything
to
> go 1 to 1-1/2 times the wind speed at any boat length. Is why I
> ask.
>
> I get the custom outfit. But 1/3 the price with half as much
room
> and with only 1/6 the hardware!?
>
> Todd
>
> --- In harryproa@yahoogroups.com.au, Mike Crawford <jmichael@>
> >
> >
>
> > The big question is why handmade boats of this size and speed
cost
> so
> > little.
> >
> > - Mike
> >
> >
> >
> > Todd wrote:
> > >
> > > I like the idea of an unstayed mast especially on a boat that
> > > doesn't need to have gobs of sail area to attain good
overall
> speed.
> > >
> > > Don't really agree with you on the wire vs foil thingy, may
be
> just
> > > my misunderstanding. I don't have a formal education in
> > > aerodynamics. But doesn't frontal area and cord width play a
> part in
> > > your apple vs an orange theory ;) I wonder what the out come
> would
> > > be with the same size sail for given length masts attach to
each
> > > would be?
> > >
> > > Rob,
> > >
> > > If the whole principal behind your designs are minimal
material
> and
> > > hardware then why such the high price tag $$$$$ on used
boats ?
> > >
> > > Todd
> > >
> > > --- In harryproa@yahoogroups.com.au
> > > <mailto:harryproa%40yahoogroups.com.au>, "Robert"
<cateran1949@>
> > > wrote:
> > > >
> > > > The Wharram rig makes sense to me, possibly with a curved
gaff
> to
> > > > sooth the exit. Not sure of how to set up the unstayed
mast to
> > > take
> > > > the point loading of the gaff,
> > > > Robert
> > > > --- In harryproa@yahoogroups.com.au
> > > <mailto:harryproa%40yahoogroups.com.au>, "brag_rotor"
> <brag_rotor@>
> > > > wrote:
> > > > >
> > > > > Greetings,
> > > > >
> > > > > This is a hopefully useful contribution to the debate on
> > > > > sail formats for the HarryProa.
> > > > >
> > > > > We have sailed a Wharram Tiki 30 since the '90s,
> and 'Pilgrim'
> > > > > has provided us with a source of much glee in nailing
much
> > > > > larger and supposedly faster vessels on most points of
sail.
> > > > >
> > > > > The numbers we can demonstrably repeat (especially since
our
> > > > > recent coat of bottom paint) caused some surprise when I
> posted
> > > > > them last time - apologies for my lack of tact. All
boats are
> > > > > an improvement over no boat, and it is not my place to
> denigrate
> > > > > anybody's design, multihull or monohull.
> > > > >
> > > > > Pilgrim is a small catamaran, and cannot comfortably
sustain
> high
> > > > > speed in rough water - ask my wife! Well, Olly isn't
> > > comfortable,
> > > > > anyway. We will need something more comfy and spacious
for
> our
> > > > > declining years, but I am most reluctant to give up on
the
> > > > > giant-killing fun we enjoy. Eaten any Oysters lately?
#;^p
> > > > >
> > > > > That's why we're here.
> > > > >
> > > > > We did check our numbers and have also discovered (see
PS)
> that
> > > we
> > > > > can point and foot well under main alone. So my focus is
now
> on
> > > > this
> > > > > type of mainsail, and its possible application to an
EasyRig.
> > > > >
> > > > > The Wharram Tiki Wingsail is a cunning combination of a
wrap-
> > > around
> > > > > sleeve luff and a short gaff. Usually loose-footed due
to the
> > > huge
> > > > > sheeting angle available on a cat, the rig is simple to
use.
> It
> > > > will
> > > > > reef going downwind (a major safety factor) because of
the
> loose
> > > > > sleeve luff and the weight of the gaff bringing the top
down;
> > > plus
> > > > it
> > > > > is safe to gybe all-standing due to the lack of a boom.
> > > > >
> > > > > The gaff keeps the sail area useful to the top of the
rig,
> since
> > > > > bermudan triangles lose performance rapidly as the sail
chord
> > > > shrinks
> > > > > with respect to the mast. A square-top variant is easy
to
> make;
> > > > > the gaff then becomes (in effect) a batten, but cheaper
than
> most
> > > > > modern battens-with-cars.
> > > > >
> > > > > Aerodynamics - this has been an interest of mine since
> boyhood,
> > > and
> > > > > as a student I recall our aerodynamics instructor at the
CAAE
> > > > telling
> > > > > us that even a small wrinkle or rivet can perturb the
flow.
> > > > >
> > > > > His favourite example was a wire and a foil, which I have
> > > uploaded
> > > > to
> > > > > the photos folder 'Aerodynamics and Sails' .....
> > > > >
> http://au.ph.groups.yahoo.com/group/harryproa/photos/browse/1641
> > >
>
<http://au.ph.groups.yahoo.com/group/harryproa/photos/browse/1641>
> > > > >
> > > > > This illustration is meant to focus on the importance of
very
> > > small
> > > > > things in the overall drag picture - a sailing boat, for
> > > example.
> > > > >
> > > > > Depending on the Reynolds Number....
> > > > > (http://en.wikipedia.org/wiki/Reynolds_Number
> > > <http://en.wikipedia.org/wiki/Reynolds_Number>)
> > > > >
> > > (http://www.princeton.edu/~asmits/Bicycle_web/blunt.html
> > > <http://www.princeton.edu/%7Easmits/Bicycle_web/blunt.html>)
> > > > > ....the foil could be of the order of 10x the thickness
of
> the
> > > > > wire for the same drag. This can double at very low
Reynolds
> Nos
> > > > > (Re) to around 20x - and sails run at low Re.
> > > > >
> > > > > Which suggests that a 5% imperfection might _double_ the
> drag in
> > > the
> > > > > worst case. It can, too. Some shapes are worse than a
round
> > > wire.
> > > > >
> > > > > This puts exposed masts in a poor light unless they
rotate
> > > > > very precisely. Shrouds don't look good, either. They
are in
> > > > > the low Re zone for sure.
> > > > >
> > > > > Sailmakers do have techniques for picking up some
cleaner
> flow to
> > > > > leeward of masts by putting a baggy step in the leading
edge
> of
> > > > sails,
> > > > > but it is still a disaster in terms of aircraft quality
fluid
> > > > dynamics.
> > > > >
> > > > > There is a _lot_ of improvement to be had over a
bermudan
> rig.
> > > > >
> > > > > The Wharram approach uses a deep sleeve luff, so that
the
> mast
> > > > > 'disappears' aerodynamically inside the sail, like the
spar
> on an
> > > > > aircraft wing. The cut is all-important, since smaller
> > > > imperfections
> > > > > start to matter more once the main sources of drag are
> addressed.
> > > > > Chris Jeckells made my sails, bless him.
> > > > >
> > > > > The thickness of the mast ceases to be of great
aerodynamic
> > > > importance
> > > > > when the sail is hoisted, so it can be properly plump and
> > > stiff.
> > > > Not
> > > > > too plump, since we do not want excessive drag when
reefed
> or in
> > > > high
> > > > > wind with the rig down. Fortunately the stiffness of a
beam
> or
> > > pole
> > > > > increases rapidly with diameter. Flexibility to shed
wind
> load
> > > in a
> > > > > gust could be added in the gaff - like a windsurfer's
flexing
> > > > batten.
> > > > >
> > > > > Two Tiki Wingsails are shown in the photo folder, one
seen
> from
> > > > > another boat, and one shot from on board. These are not
> Pilgrim,
> > > > > and the sails do not seem to be setting as well as ours.
A
> lot
> > > > > of people are relaxed about sails, and as I have
admitted to
> > > Rob,
> > > > I'm
> > > > > a pestilentially picky perfectionist when it comes to
sail
> shape.
> > > > >
> > > > > Wrinkles may be common - but I prefer them on other
people's
> > > sails,
> > > > > not mine! Remember the wire and the foil. A 5% wrinkle
> > > > > might double the drag - so how about lots of small
wrinkles?
> > > > >
> > > > > The two photos are there to show the Wharram wingsail -
more
> at:-
> > >
> > > > > http://www.wharram.eu/photos/index.cgi?
mode=album&album=Tiki-
> > > <http://www.wharram.eu/photos/index.cgi?
mode=album&album=Tiki->
> > > > range/Tiki-30
> > > > >
> > > > > So what do you folks think, is there a case for using a
> Wharram
> > > > > sleeve luff/gaff combination on a HarryProa EasyRig?
> > > > >
> > > > > All the best, Ben
> > > > >
> > > > > PS
> > > > > About that run up the coast of Lanzarote in January
under
> main
> > > > > alone - lazy skipper, should have reefed both main and
genoa.
> > > > > But we learned something interesting....
> > > > >
> > > > > The tack was 88 degrees on the GPS (and compass - near as
> > > > > one can tell on a compass) and we started footing upwind
at
> > > > > nearly 9 GPS knots. Tricky to get a main flying spot on
> without
> > > > > any genoa telltales, but eventually we had 9 knots -
roughly-
> > > > > showing on the GPS. Pretty good, I thought vaguely. It
was
> > > > > a pleasant surprise to point so well under main alone,
which
> > > > > is not usually our custom.
> > > > >
> > > > > Sea was bumpy, hence the reduced rig.
> > > > >
> > > > > Afterwards I had a look at the GPS points I'd put in and
> > > > > from the times did a speed over ground by hand, which was
> > > > > 8.8 knots, and 8.8/16 is 55% of max wind speed measured
> > > > > 1/3 the way up the mast. 8.8/14 is 63%, so we were going
> > > > > pretty well even without a genoa.
> > > > >
> > > >
> > >
> > >
> >
>
>
>
>
>
>
> ----------------------------------------------------------
-----------
>
>
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> Checked by AVG Free Edition.
> Version: 7.1.394 / Virus Database: 268.18.2/692 - Release Date:
2/18/2007
>


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