Bow burrying is one of my concerns with this design, any one
considered if the addition of side lifting strakes would improve
this characteristic? drag wise eventually would be less or similar
to lenghtening the hull.
Regarding the reported drag streams at the rudders, it looks like
this is what we call in hydrodynamics 'ventilation' . To cure this
in a previous catamaran I owned, with stern hung rudders, I used a
suggestion from the Marchaj(?)book, adding a ring of about one
inch wide perpendicular to the rudder profile and paralel to the
water line, in my case in line with the continuation of the hull
(5CM deep) but in the case of side hung rudders I would place them
deeper in a way to never be exposed above water surface even when ww
hull flies.
My rudders became much more responsive (just like on a rail track)
and ventilation disapeared.
rgds,
Nuno
--- In harryproa@yahoogrou
wrote:
>
> G'day,
>
> Excellent! Any idea how quick it goes with the hull up? How much
wind to
> get it flying? Have you got a plan for it it goes over? The
masts will
> float, but make sure they are tied into the boat or it gets messy
when the
> boat is on it's side with the masts pointing upwind. The hulls
blow down
> wind and the masts stay where they are.
>
> regards,
>
> Rob
>
> On Feb 14, 2008 10:35 AM, Doug Haines <doha720@...
>
> > Hi,
> >
> > Sailing getting up in air easily, steering to controllift. Nose
not
> > digging too bad, but rudder develops those drag streams -
separation off the
> > foil at about time get airborne. Not fair enough after adding
extra
> > elongation recently
> > Doug
> >
> > *Doug Haines <doha720@...
> >
> > Hi,
> >
> > Sailing's been pretty good lately, fast and fun, and mostly dry.
> > I get to the limit of my nerves or of the boat fairly easily
now - the ww
> > hull has definitely been up out of the water, immediately at
which time I
> > dumped sheet.
> > The other thing that is limiting is the bow burying into the
water. It
> > could probably take more submersion, but I get too scared and
ease off. The
> > hull is lifting up a bit usually at about the time that the bow
is digging
> > in a lot, so all in all I just ease sheets and speed drops back
to like 9-10
> > knots. The top speed has been around 13-14 knots. Using GPS lent
to me.
> > FAirly satisfied with that I guess.
> > Sail are could stay the same and a longer lw hull would increase
speed a
> > lot. My overall beam is very narrow only 3.?m and is about right
for current
> > dimensions of rest of boat.
> > Extra metre beam would combine with a longer lw hull and make
more speed
> > possible.
> >
> > Maybe harrygami size lw hull, 4.5m overall beam, and two
schooner masts
> > with just a bit more area than mine with flat heads/fat heads
sail tops.?
> >
> > Good enough as is though. Tough enough to anchor (pulling up),
lots of
> > windage, especially when sails hoisted, woudn't like any more
work than
> > already have.
> >
> > Doug
> >
> > *Rob Denney <harryproa@.
> >
> > G'day,
> >
> > I have put some photos in the Files section (not sure why I
didn't put
> > them in Photos). They are not pretty and it is definitely time to
> > paint all the changes and mistakes, but they work. Any
questions, let
> > me know.
> >
> > regards,
> >
> > Rob
> >
> > On Jan 21, 2008 5:55 PM, Jim Baltaxe
<jim.baltaxe@
> > wrote:
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > Hi Mark &al
> > >
> > > Any chance of some photos or drawings of the beam mounted
rudders?
> > >
> > >
> > >
> > > Enjoy
> > >
> > > Jim Baltaxe
> > >
> > > They said, get a life. I looked on TradeMe but I couldn't find
one.
> > > ____________
> > > From: harryproa@yahoogrou
40yahoogroups.
> > harryproa@yahoogrou
> > > Behalf Of Mark Stephens
> > > Sent: Tuesday, 15 January 2008 11:20 p.m.
> > > To: harryproa@yahoogrou
40yahoogroups.
> > > Subject: Re: [harryproa] Re: Anyone there ?
> > >
> > >
> > >
> > >
> > >
> > > The biggest negative about the hull hung rudders, well the mk
2 version,
> > is
> > > they would be difficult to replace once the shear pins broke.
At the
> > moment
> > > they are designed to 'break away' in the event of a collision.
You would
> > > then have to retrieve them from the end of the attachment line
and refit
> > > them with new shear pins. This may seem like a big
disadvantage but it
> > will
> > > only happen in a catastrophic event which would render any
catamaran
> > with a
> > > stuck and broken daggerboard at best and a split hull and bent
rudder
> > shaft
> > > at worst.
> > >
> > > We are not in the business of selling boats using boatshows and
> > brochures.
> > > We are enthusiasts trying to promote the proa as a viable
alternative to
> > > people who understand that Harryproas don't have the decades of
> > development
> > > other multis have. Some things, rudders in particular, will go
through
> > many
> > > iterations before the perfect solution is reached and we keep
all of our
> > > developments transparent. Maybe not commercially sensible but
that's not
> > > what we are about. I'm sure all those subscribed to this group
are here
> > > because of this.
> > >
> > > Hopefully the beam mounted rudders will prove to be the best
option. Rob
> > has
> > > experimented with them and they seem to be working well. The
biggest
> > concern
> > > was the distance from the boats centre but this has proven OK
on
> > > Elementarry. Blind Date will be trying them as will Solitarry.
As they
> > will
> > > kick up in both directions and won't be as draggy let's hope
they prove
> > > successful.
> > >
> > > Mark
> > >
> > > Rob Denney wrote:
> > >
> > >
> > >
> > > G'day,
> > >
> > > The side of hull mounted rudders work well, as did the in hull
dagger
> > > rudders before them and the in hull spade rudders before them.
They
> > > are far better than the rudders and daggerboards in most
multihulls.
> > > However, none were the perfect solution and this is what we are
> > > looking for. The beam mounted rudders are another (quite
large) step
> > > in this direction and have been tested by me on my
Elementarry, and
> > > now on my solo boat. They will then be included in the plans.
> > > Anyone who is now at the rudder stage of their build should
discuss
> > > the options before they proceed.
> > >
> > > Because I believe it is in everyone's interest if I am upfront
about
> > > what we are doing and give details of experiments that have
been tried
> > > (rail mounted riudders etc) there is a lot of discussion.
These are
> > > ideas, not "designs" and they may or may not end up on the
plans.
> > >
> > > Rudders and daggerboards/
almost all
> > > boats. We are trying to reduce the potential for damage,
reduce the
> > > cost and improve the performance rather than taking the stance
of the
> > > rest of the industry that there is nothing that can be done
about it
> > > and that it is normal for daggerboards to break and hulls to
split
> > > when they collide with something and that boats should be
confined to
> > > deep water because of the depth of their rudders.
> > >
> > > The side of hull rudders in dagger cases do hit a fair bit of
water
> > > as can be seen in the Rare Bird video. They may or may not be
> > > draggier than the conventional slot for daggerboards. They are
not
> > > likely to cause any handling problems and the spray they kick
up is
> > > not likely to reach the cockpit. They do have the advantage
that in a
> > > collision, they kick up and in storms, shallow water and on the
> > > mooring, they can be lifted. Their biggest advantage is that
in the
> > > event of damage, there are no holes below the waterline.
> > >
> > > The beam mounted rudders keep all these advantages and solve
the spray
> > > problem. They are also considerably easier to build.
> > >
> > > regards,
> > >
> > > Rob
> > >
> > > On Jan 15, 2008 1:54 PM, Jim Baltaxe
<jim.baltaxe@
> > wrote:
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Hi Robert
> > > >
> > > > If what you say about the rudders is true then why is there,
or has
> > there
> > > > been, so much worrying about the design of the rudders? Rob
and others
> > > have
> > > > been concerned about the lower brackets being caught by
waves, designs
> > > have
> > > > been posted for rudders hung from the akas and there was
even a
> > proposal
> > > to
> > > > hang rudders from stub akas. I'm not even talking about
hanging a
> > single
> > > > rudder/daggerboard from a track on the lee hull and hauling
it end to
> > end
> > > > during a shunt.
> > > >
> > > > I am aware that there are other things than simple strength
or turning
> > > > moment involved in rudder design but it seems to be received
knowledge
> > > that
> > > > rudders are the "Achilles heel" of proas.
> > > >
> > > >
> > > >
> > > > Enjoy
> > > >
> > > > Jim Baltaxe
> > > >
> > > > They said, get a life. I looked on TradeMe but I couldn't
find one.
> > > > ____________
> > > > From: harryproa@yahoogrou
40yahoogroups.
> > harryproa@yahoogrou
> > > On
> > > > Behalf Of Robert
> > > > Sent: Monday, 14 January 2008 4:01 p.m.
> > > >
> > > > To: harryproa@yahoogrou
40yahoogroups.
> > > > Subject: [harryproa] Re: Anyone there ?
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > -Hi Jim,
> > > > I was certainly impressed with the build when I saw 'Aroha'
in the
> > > > earlier stages- I even helped with a bit of the fairing on
one of the
> > > > rudders so it must be good! I cant see any problems with the
rudders
> > > > as far as slowing the boat down and Rare Bird was a good
pilot study
> > > > for the robustness. The brackets are strong enough to take
the sailing
> > > > loads so the bit of slapping won't worry them. There is not
much
> > > > increase in wetted area if the brackets hit a wave and it
would damp
> > > > even further the minimal chance of hobby horsing, which
could actually
> > > > improve performance. (I reckon they also provides a means of
getting
> > > > on board again from in the water)
> > > > Coming over bars is a good test for robustness
maneuverability and
> > > > handling.
> > > > Wish you well in the legal wrangles,and I am sure that Bain
would be
> > > > happy for Aroha to go to a good home,
> > > > Robert--
> > > >
> > > >
> > > > In harryproa@yahoogrou
40yahoogroups.
> > Baltaxe" <jim.baltaxe@
> > > > >
> > > > > Hi Robert
> > > > >
> > > > > I did get out onto him/her on the last day before Bain so
kindly
> > took me
> > > > > to the airport, but unfortunately it was pelting down like
mad. We
> > rowed
> > > > > out to the boat, moored in a river near Bain's house and
had a good
> > look
> > > > > around but never got off the mooring. We had neither the
time nor
> > the
> > > > > breeze to prove much.
> > > > >
> > > > > The boat appears to be very well built and very much what
I do want.
> > > > > Enough room for one or two people for extended coastal
cruising and
> > the
> > > > > pop-up canopy over the upper cockpit was a cozy place for
us to
> > shelter
> > > > > in the rain and talk about, as well as look at, the boat.
> > > > >
> > > > > My only real reservation about the design is the ongoing
question of
> > > > > rudder attachments. Aroha's appear solid but the lower
brackets
> > > > > certainly will certainly be caught in almost anything more
than a
> > flat
> > > > > sea. I really don't know whether that would make much
difference to
> > > > > overall performance, though.
> > > > >
> > > > > I did see Aroha come across the bar into the river a
couple of days
> > > > > earlier and it was an impressive sight.
> > > > >
> > > > > I am still working on the legal and financial issues so I
am hoping
> > that
> > > > > I will be able to make a reasonable offer fairly soon. In
the
> > meantime,
> > > > > I do wish Bain good luck and if I miss out, so be it. If
everything
> > > > > works well, perhaps I'll be able to get across for another
look and
> > a
> > > > > ride later this year.
> > > > >
> > > > > Enjoy
> > > > >
> > > > > Jim Baltaxe
> > > > >
> > > > > They said, get a life. I looked on TradeMe but I couldn't
find one.
> > > > >
> > > > > ____________
> > > > >
> > > > > From: harryproa@yahoogrou
40yahoogroups.
> > harryproa@yahoogrou
> > > >
> > > > > On Behalf Of Robert
> > > > > Sent: Thursday, 3 January 2008 11:58 p.m.
> > > > > To: harryproa@yahoogrou
40yahoogroups.
> > > >
> > > > > Subject: [harryproa] Re: Anyone there ?
> > > > >
> > > > >
> > > > >
> > > > > -G'day Jim,
> > > > > Sorry to hear of your difficulties. Not a nice situation
but there
> > can
> > > > > be an afterlife
> > > > > Did you get a chance to sail on Aroha?
> > > > > Robert
> > > > >
> > > > > -- In harryproa@yahoogrou
40yahoogroups.
> > > >
> > > > > <mailto:harryproa%
> > > > > <jim.baltaxe@
> > > > > >
> > > > > > Hi Robert &al
> > > > > >
> > > > > > I'm in exactly the same position which is why I've had
my head
> > down
> > > > > for
> > > > > > a while, since Derek's workshop and my visit with Bain.
I'm still
> > > > > trying
> > > > > > to work out the "disengagement" (what else do you call
a "divorce"
> > > > > from
> > > > > > a legally recognised, long-term, relationship?
perhaps I
> > can
> > > > > > get the money together. Sorry Bain but I am trying,
really hard.
> > > > > >
> > > > > >
> > > > > > Enjoy
> > > > > > Jim Baltaxe
> > > > > > 209 Derwent Street
> > > > > > Island Bay, Wellington
> > > > > > NEW ZEALAND
> > > > > > +64 (04) 938 6018
> > > > > > 027 563 5018
> > > > > > They said, get a life. I looked on TradeMe but I
couldn't find
> > one.
> > > > > >
> > > > > > ____________
> > > > > >
> > > > > > From: harryproa@yahoogrou
40yahoogroups.
> > > >
> > > > > <mailto:harryproa%
> > > > > [mailto:harryproa@yahoogrou
40yahoogroups.
> > > >
> > > > > <mailto:harryproa%
> > > > > > On Behalf Of Robert
> > > > > > Sent: Thursday, 20 December 2007 4:16 p.m.
> > > > > > To: harryproa@yahoogrou
40yahoogroups.
> > > >
> > > > > <mailto:harryproa%
> > > > > > Subject: [harryproa] Re: Anyone there ?
> > > > > >
> > > > > >
> > > > > >
> > > > > > -waiting with bated breath for the next development of
the Harry.
> > Love
> > > > > > to see the promised photos of Sidecar and Solitarry I am
still
> > keen to
> > > > > > get a Harry but health and wealth defy me. The concept
still makes
> > the
> > > > > > most sense to me and the boats out there look pretty
good. If I
> > had
> > > > > > the cash I'd probably just buy Bain's Aroha and get
sailing.
> > > > > > Meanwhile I'm investigating doing a KSS system using
polyprop and
> > > > > > epoxy with an end bulkhead with foam ends.
> > > > > > Robert
> > > > > >
> > > > > > -- In harryproa@yahoogrou
40yahoogroups.
> > > >
> > > > > <mailto:harryproa%
> > > > > > <mailto:harryproa%
> > <vertiges59@
> > > > > > wrote:
> > > > > > >
> > > > > > > Nobody more in this group ?????
> > > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > > ____________
> > >
> > > No virus found in this incoming message.
> > > Checked by AVG Free Edition.
> > > Version: 7.5.516 / Virus Database: 269.19.2/1224 - Release
Date:
> > 14/01/2008
> > > 5:39 PM
> > >
> > >
> > >
> > >
> >
> >
> > ------------
> > Support the World Aids Awareness campaign this month with Yahoo!
for
Good<http://us.rd.
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> >
> >
> > ------------
> > Yahoo! Answers - Get better answers from someone who knows. Try
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now<http://uk.answers.
xOTAEc2VjA21haWwEc2
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>
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